The similarity approach stands as a significant attempt to defend scientific realism from the attack of the pessimistic meta-induction. The strategy behind the similarity approach is to shift from an absolute notion of truth to the more flexible one of truthlikeness. Nonetheless, some authors are not satisfied with this attempt to defend realism and find that the notion of truthlikeness is not fully convincing. The aim of this paper is to analyze and understand the reasons of this dissatisfaction. Our thesis is that the dissatisfaction with the notion of truthlikeness concerns the double role that this notion plays within the similarity approach: This notion plays both a regulative role in the conception of theories and a constitutive one i...