Recent academic debates about film criticism in the digital era have mostly focused on the practice of professional critics. This chapter aims to reorient the debate on amateur critics and film fans who have been largely seen as an anonymous force that threatens the critical establishment. How, then, can we better grasp how fans disrupt existing critical practice? Drawing on the actor-network theory and ideas related to the postcritique movement, this chapter argues that the disruptive nature of fan criticism can be best captured through its affective ambiguity. While centering on one popular and controversial Czech fan critic and his film reviews, this chapter introduces the concept of mischievous criticism; a style of writing that is both hateful and playful, abusive and appreciative. Such affective ambiguity is crucial to understanding not only the provocative nature of mischievous criticism, but also its role in the circulation of hate, its approach to film evaluation and its relationship to online communities. Finally, framing film criticism in terms of its mood, style and dominant affect allows us to expand the notion of emotional labor. As this chapter suggests, such labor may also include cultivation of affectively rich, polarizing personas or inventive manipulation of language.