A growing body of research has discovered that even the trivial attribute of similarity, that is, incidental similarity, will have significant favorable impact on initial social interactions (Burger et al. 2004; Guéguen, Pichot, and Le Dreff 2005; Jiang et al. 2010; Martin and Guéguen 2013). Incidental similarities are chance similarities between individuals, such as a shared first name or birthplace, which create a sense of association between two people (Burger et al. 2004). Prior research shows that people who perceive they share a birthday, first name, or similar fingerprints with a stranger are more likely to comply with the stranger’s request (Burger et al. 2004; Guéguen, et al. 2005) and are more willing to respond to the stranger’s questions on intimate topics (Martin and Guéguen 2013). Jiang et al. (2010) applied these findings in a service interaction context and found that incidental similarities between consumers and service providers will increase consumers’ liking for the services and purchase intentions. The key reason for these favorable impacts is that an incidental similarity creates a sense of connectedness between two strangers. This sense of connectedness creates a unit relationship between two strangers that is not shared by other people around them. Therefore an incidental similarity generates a fleeting sense of liking and it has been linked to positive affect (Burger et al. 2004) and interpersonal attraction (Insko and Wilson 1977). Although existing research suggests that incidental similarities lead to favorable reactions to the similar other, we propose that the effects of incidental similarities are not invariably favorable. Incidental similarities can elicit unfavorable effects, and can make an otherwise disinterested observer become involved in an exchange between a stranger and a company that (s)he merely witnessed. For example, a service failure involves the service provider and the suffering customer. From the perspective of an individual observing the failure, the nature of the effect of incidental similarities would depend on whether one feels a sense of association with the provider or the customer. Imagine a situation in which someone observes a customer being told that a table he had reserved is actually not available. If the observer notices that customer’s surname happens to be the same as his own, he may be disposed to view the situation from the customer’s perspective and blame the provider for the failure. However, if the observer notices from the provider’s name tag that they happen to have the same surname, he may feel more similar to the provider and attributing him less responsibility for the failure.