1. Introduction

Did you know that 75% of consumers trust influencer recommendations over traditional advertisements? [1]. In the digital age, influencer marketing is considered as an effective marketing tool, and its global investment and market size globally reached $148 million in 2019 and is expected to exceed $373 million by 2027[2].

Influencer marketing has benefits such as high cost-effectiveness and other advantages [3].

Influencers are a value exchange for marketers and are usually seen as ambassadors for brands [4]. Moreover, the recommendation of a product given by tweets by influencers can increase value and help in the consumption decision process [5]. Twitter also conducted a powerful study that found that 40 percent of Twitter users make purchase decisions as a direct result of a Tweet from an influencer. While the utilization of social media influencers aims to promote products more attractively, the outcomes of such marketing efforts remain variable.

Influencer marketing has significant benefits, but it is still unclear what work and what does not work in influencer marketing campaigns. Therefore, the objective of this study is to identify the key factors that contribute to the success of influencer marketing campaigns. For instance, how can brands rely on influencer trustworthiness and content authenticity to affect consumer engagement and brand trust? Specifically, we investigate how brands can use influencer marketing to foster customer engagement, loyalty, credibility, and other desirable outcomes. By exploring these issues, this study improves the understanding of digital marketing strategies and provides insights for influencing influencer partnership practitioners. This is done through case studies, which allow us to identify best practices that influence marketing.

2. Literature review

Previous studies have shown that the key factors influencing influencer marketing can be categorized into credibility, content quality, data analysis, and feedback. These aspects determine the effectiveness of influencer campaigns. The existing literature highlights the importance of understanding these factors to design more successful marketing strategies, this paper aims to further explore how the target customers, consumer trust, and engagement these three factors interact with each other. Communicate accurately with consumers to ensure that marketing content is relevant. Trust is built on authentic, consistent content that contributes to purchasing decisions and brand loyalty. A high level of customer loyalty not only increases brand loyalty but also provides important market feedback that helps the brand to continuously optimize and improve. Research and industry practice shows how closely these factors are linked and how important they are to the success of marketing campaigns.

2.1. Target consumers

The effectiveness of influencer marketing largely hinges on accurately understanding the target consumer. For example, according to Influencer marketing and its impact on consumer lifestyles, it helps businesses develop a brand and retain customer loyalty since the target audience trusts certain people whom they know and follow [6]. That is when personal relationships acquire a new meaning for the current marketing strategies. Successful brands can ensure precise market segmentation and targeting by detailed and complex socio-demographic and psychographic features. These features can be addressed by influencers. Demographics, age, gender, occupation, and socioeconomic status are key factors.

The power of the purse notes that women now have a dominant say in most of the purchasing decisions and, every year, direct control over trillions of dollars in new wealth [7]. Is significant economic influence of women, often referred to as “the power of the purse.” The report goes further to identify that high-income groups are inclined to product quality and brand reputation, while low-income groups are put under economic pressure to be keen on product pricing and practicality [8]. Having content that matches the target audience demography can be engaging as a result.

Moreover, psychological factors like interests, lifestyles, and values play a very significant role too. The content will be able to create a deeper affinity if it is resonant with the identity and lifestyle of the audience. For instance, an eco-friendly audience may prefer promoters on environmentalism, while a health-conscious audience will prefer exercise and diet promoters [9]. Moreover, ‘fit’ becomes an important factor between the influencer and his audience. According to [10], studies show that influencers with a natural fit between them and the audience in terms of preferences and values are more persuasive, and this improvement in alignment grows the genuineness and relevance of the influencer’s content. This statement puts the emphasis on connecting the influencer with the values of the audience. Research shows that content that matches the audience’s preferences is more persuasive. Therefore, this paragraph proposes the following hypothesis:

H1: The higher the effectiveness of influencer marketing, the more accurate the targeting.

2.2. Consumer trust

Trust is an essential element of the relationship between influencers and consumers. It refers to consumers' belief in influencers' recommendations. According to the principle of reciprocity, trust and loyalty are built on successful social exchanges between influencers and followers.

In the reciprocal process of followers being satisfied and influencers getting likes and comments, the trust relationship becomes stronger. Research has consistently shown that trust positively influences purchase intention, it can lead to desirable marketing outcomes. When consumers trust an influencer, they are more likely to consider their recommendations and make a purchase based on their endorsements. Trust plays an effective role in conducting influencer marketing campaigns on brand attitude and word-of-mouth (WOM) intention[11].

Authenticity is a key factor that influences trust in influencer marketing. Consumers may have higher willingness to pay with authentic contents from the influencers that they follow [12], because they can feel sincerity, intimacy. The congruence between the influencer’s content and expertise foster trust [13]. Therefore, this paragraph proposes the following hypothesis:

H2: The higher the trust between customers and influencers, the higher the effectiveness of influencer marketing.

2.3. Engagement

Following reasecrch concept, customer engagement is defined as "the customer is cognitive, emotional, and behavioral activities" [14]. Engagement refers to the effect of an individual's participation and connection with the organization's offerings or organizational activities, initiated by either the customer or the organization [15]. This definition becomes particularly relevant in the context of influencer marketing, where the perceived fit between influencer marketing content and customer needs is crucial [16]. When the content shared by influencers aligns well with what customers are looking for, it significantly enhances user engagement. Consistently high-quality content keeps the audience interested and sustains their engagement over time. Moreover, consumers tend to prefer products endorsed or recommended by influencers because they find this information more persuasive [17]. Consequently, the expertise and credibility of influencers play a vital role in maintaining audience interest and building a loyal follower base. By leveraging the expertise of influencers and creating content that meets customer needs, it is possible to increase the interaction between influencers and customers, thereby increasing engagement. Therefore, this paragraph proposes the following hypothesis:

H3: The higher the engagement between customers and influencers, the higher the effectiveness of influencer marketing.

3. Methodology

In this paper, we adopt a case study approach as our method to testify hypothesis. The primary sources for our research include both successful and unsuccessful influencer markting strategies, ensuring our study is grounded in reliable empirical evidence. The study primarily investigates the strategic choices in influencer marketing, the challenges encountered during implementation, and the dynamics of strategic adjustments. By using the multiple cases, our study may investigate the influencer marketing strategy critically with a holistic view from its benefits and drawbacks.

4. Case study

4.1. Case study 1: Gymshark’s influencer marketing strategy and user engagement

4.1.1. Background

Founder Ben Francis launched Gym shark in 2012 as a fitness apparel and sports accessories brand, starting from his garage. Fast forward eight years, Gym shark has achieved an impressive valuation of $1.3 billion and boasts a dedicated following across more than 100 countries and territories. In 2019 alone, the company recorded sales of £175.2 million. This section delves into Gym shark’s social marketing strategy, with a particular focus on its remarkable success on TikTok, while also examining how it effectively targeted customers and fostered user engagement to achieve such extraordinary accomplishments.

4.1.2. Target customer

Gym shark is aimed at 18–25-year-olds who love fitness, fashion and music. By strategically partnering with influencers whose interests and lifestyles align, the brand effectively engages its core target audience. Launched by Gym shark, the '66 Day Fitness Challenge' focuses on the health, fitness and dance categories and has successfully attracted many individuals dedicated to these areas.

4.1.3. Increased user engagement

Influencers have played a key role in promoting Gym shark’s "66 days fitness challenge", significantly increasing user engagement. Participants were asked to upload an initial photo of themselves and share a new photo 66 days later for comparison. The final winner will receive exclusive access to the merchandise for free for a full year. Through this interactive model, Gym Shark has a total of more than 18 million followers on social media and 14 online stores with customers in more than 230 countries. Therefore, users not only actively participate in the brand's activities, but also become an integral part of the brand narrative. Drive engagement and conversion rates by resonating with your target audience through authentic and relevant influencer content. This deep engagement is consistent with consumer engagement theories that emphasize cognitive, emotional, and behavioral engagement in brand interactions.

4.1.4. Conclusion

Through a carefully planned and perfectly executed influencer marketing strategy, Gym shark has successfully grown from a humble garage brand to a globally recognized fitness brand. This case illustrates the importance of influencer marketing in contemporary brand competition and demonstrates the practical application of effective targeting and consumer engagement. This case study provides support for H1 and H3.

4.2. Case study 2: Emirates Airline’s partnership with Kara and Nate

4.2.1. Background

Emirates is one of the world's largest international airlines, renowned for its luxurious cabin configuration and excellent service. Carla and Nate are a popular YouTube influencer as travel vlogger. Emirates invites them to experience it. The video “33 Hours in the World's Best First Class,” was published then in the social media platforms, showcasing the luxurious Emirates First Class experience with detailed admiration.

4.2.2. Audience engagement

The videos produced by Kara and Nate show a detailed flight experience and thoughtful service, which attracts a large audience to watch and interact with them. Viewers commented on the luxury Emirates trip and expressed interest in flying on Emirates.

4.2.3. Authenticity and trust

Famous Vlogger's authenticity and objective narrative established a strong connection with viewers. They gave a detailed description of the interior of the cabin such as a380 suite’s structure, they experienced the amazing airplane bar and had a showering on the plane. They often exclaim or make comments, and their passionate and detailed reporting adds credibility, making viewers more likely to trust their choice and consider Emirates in the future.

4.2.4. Conclusion

By leveraging the influence of the Vlogger, Emirates successfully presented its premium First- Class product to a global audience, reinforcing its brand as a leader in luxury air travel. At the same time, this cooperation expands the influence of the brand, increasing its awareness and loyalty. This case study provides support for H2 and H3.

4.3. Case study 3: Chiara Ferragni's "Charity Cake" scandal

4.3.1. Background

This case study discusses the Italian influencer Chiara Ferragni’s trust crisis in 2023 in collaboration with the Italian cake brand Balocco. Chiara Ferragni was an influencer with over a million followers. She came together with Balocco to launch a special edition Christmas cake, whereby some percentage of the revenue from each sale would be channeled to charity. The cakes were branded with Ferragni's logo and sold at a higher price than regular cakes.

4.3.2. Event details

Investigations revealed that the actual charitable donation was far less than advertised. Only a one-time donation of 50,000 euros was made before the cake launch, rather than ongoing donations from the sales proceeds. This misleading advertising led to consumer outrage and resulted in fines of 1 million euros for Ferragni and 420,000 euros for Balocco. Additionally, the Milan prosecutor's office launched an aggravated fraud investigation against Ferragni and Balocco's president.

4.3.3. Trust

Trust, a cornerstone of influencer marketing, was significantly undermined in this case. Consumers were misled into believing that a portion of the cake sales would be donated to charity, which was not true. This breach of trust had several repercussions. The consumers felt betrayed by both Ferragni and Balocco, which is likely to lead to a lasting reputational crisis for both the influencer and the brand. Influencers operate under high standards of authenticity, and once credibility is lost, it becomes challenging to restore. As a result, customers who have been deceived are less likely to support and purchase from Ferragni and Balocco in the future. This erosion of trust contributes to a decline in brand loyalty and the potential loss of loyal customers. The scandal attracted widespread media attention, further undermining trust. Coverage of the fines and legal investigations amplified the negative impact, spreading the story of betrayal to a larger audience.

4.3.4. Analysis

This case study provides a perfect example of what happens when trust is eroded in the relationship between an influencer and her followers. Rebuilding trust requires significant effort and time. Ferragni’s apology and pledge to donate were initial steps, but sustained transparency and consistent ethical behavior are essential for restoring consumer confidence. Influencers and brands must prioritize honesty and integrity in their campaigns to maintain and rebuild trust (see Table 1).

Table 1: Summary of three case study

4.4. Conclusion for three case study

Chiara Ferragni's "Charity Cake" scandal highlights the importance of target consumers and trust in influencer marketing. Misleading advertising undermined consumer trust, reduced engagement, and negatively impacted the brand image. This case study provides support for H2, showing what happens (i.e., the negative consequences) when trust is lacking.

5. Discussion

Case study 1 confirms the hypothesis that strategic influencer collaboration can significantly increase brand awareness and engagement, that is, the more accurate the audience target, the higher the success rate of influencer marketing. Case study 2 show the partnership between Kara and Nate and Emirates Airlines, which serves as a typical case study of influencer marketing, demonstrating the significant impact that trust and engagement can have on brand promotion. Rather, case study 3 this failed example underscores the assumption that trust is a foundational element of influencer marketing. In this case, the breach of trust led to multiple negative outcomes, including consumer betrayal, loss of credibility, declining brand loyalty, and widespread negative publicity. Scandals have shown that once trust is broken, it is difficult to rebuild, and the reputation of influencers and brands can suffer long-term damage.

Comparing these cases provides valuable insights into influencer marketing dynamics. Gym shark and Emirates demonstrated the successful strategy of strengthening the strong connection with the audience through target positioning and authenticity and enhancing brand awareness and trust. In contrast, the Chiara Ferragni case highlights the vulnerabilities that exist in influencer marketing, particularly misleading claims and their damage to trust and reputation. These cases also show that while influencer marketing can significantly increase brand awareness and engagement, it requires careful planning and ethical execution to maintain and build consumer trust.

All in all, these cases together highlight the key elements of successful influencer marketing: effective targeting, authentic engagement, and unwavering trust. Brands must carefully choose influencers that align with their values and audience expectations. The authenticity of promotional content is essential to build and maintain trust. In addition, transparency and ethical behavior are essential to avoid the pitfalls of misleading marketing practices. These insights provide a framework for brands seeking to effectively leverage influencer marketing, highlighting both the opportunities and potential challenges inherent in this strategy.

6. Implications for managers

Based on the above analysis of influencer marketing strategies and their outcomes, we proved influencer marketing is one of the significant tools for brand promotion. Managers should therefore target the targeted consumers in a very precise manner and understand thoroughly the demographic and psychological characteristics of the audience, to be in line with the brand values in choice of users. This way, it can have brand content that is more relevant and increases user engagement. Building and maintaining consumer trust is paramount. It would make the brand more credible and make the consumers more predisposed to making a purchase. In a highly competitive environment, managers should also develop interactive marketing promotions that engage the consumers' behavior and communicate through cross-platform promotion. Therefore, constant monitoring and measurement of marketing activities with further strategic customization towards feedback from data would optimize the effectiveness in marketing. Lastly, the managers need to adhere to the code of ethics and ensure honesty and transparency in all marketing activities to restore and rebuild the consumers' faith. A well- designed set of strategies successfully implemented would have the brands standing out amidst a highly competitive market and assured long-term brand loyalty and credibility.

An additional, point for managers is the buying power associated with follower volume linked to the influencer’s size. It is misplaced because a large number of followers do not mean high purchasing power. Though influencers with a large following do provide extensive reach, their followers may not have a strong purchasing intention or capability. Conversely, micro- influencers often have a high level of engagement due to their low-level but more concentrated audience type. Consequently, these followers could have higher purchase behavior because of an innate sense of the realness and relatability factors of the influencer. Therefore, it is important that quality in engagement and characteristics in audiences are assessed by managers when gauging potential purchasing power, rather than simply the count of followers. by focusing on these aspects, brands can better target consumers who are more likely to convert, ensuring a higher return on investment.

7. Conclusion

Influencer marketing has become a powerful tool for brands to increase awareness and consumer engagement in the digital age. It is essential to figure out what makes influencer marketing work. This article selects three representative influencer marketing cases. Together, these examples highlight that successful influencer marketing depends on effective targeting, authentic engagement, and maintaining trust. While these cases provide some insight, they may fail to include diversity across industries and regions. In addition, case selection bias may also affect the objectivity of research results. Future studies should be as broadly applicable as possible. In short, the brand must cooperate with influencers who resonate with their values, ensure the authenticity of its contents, and adhere to the moral standards, in order to maintain the trust of the consumer.

Acknowledgment

Yuemeng Yu, Zimeng Tang, Zhifei Han contributed equally to this work and should be considered co-first authors.