Social networking sites (SNSs) are invested in heavily by marketers aiming to reach a growing number of consumers. Concerns regarding the influence of posts displayed on SNSs in relation to behaviour were raised, in particular the promotion of ill-health behaviour directed to adolescents who may be at risk from suggestible practices. Although adolescents tend to be critical towards traditional forms of advertising, little is known about their perception of influencing strategies developed online, especially where sponsor- and user-generated content coexist. This exploratory study aims to gather information directly from adolescents about their use of SNSs their awareness of the influence that SNS content may have, particularly when it comes to tobacco and alcohol messages. Ten focus groups were conducted with 39 adolescents (11–16 years old; 56.4% male). Qualitative analysis documents the differences associated with adolescents’ favourite SNSs. The different parameters linked to each SNS and the expectation to find entertaining content and values associated with friendship may decrease adolescents’ perception of potential risk for health associated with SNS use. Authors advocate for the development of educational programs based on eHealth literacy and the use of social marketing techniques to facilitate and motivate adolescents to develop their competences.