• brand transgression
• customer-brand relationships
• negative emotions
• social media communication
• unethical advertising

The present dissertation aims to contribute to the literature on negative customer-brand relationships, by addressing the issue of brand transgressions in advertising in social media communication. Under the theoretical lenses of the cognitive theory of emotions, consumers’ emotional and behavioural reactions to brand transgressions in advertising are investigated. To this goal, a first explorative study through in-depth interviews, and two online experiments were conducted. Main findings revealed that brand transgressions in advertising may seriously affect the quality of the customer-brand relationship leading to negative attitude toward the ad and the brand when moral outrage mediate this relationship and to brand avoidance, negative word-of-mouth, and other protest behaviours (i.e. boycotting, participation to online anti-brand communities) when brand hate mediates this relationship. Brand aversion is amplified by the presence of user’s negative comments referred to the ad and the brand. Managerial and theoretical implications are discussed at the end of this dissertation.