Risk for sexually transmitted infections (STIs) is perceived to be less when the potential partner is sexually appealing. Is it possible that cleanliness of the room in which intercourse takes place also affects perceived risk for STIs? In scenario studies, participants were asked to imagine having had unsafe sex with a person they just met in that person's apartment (Study 1) or in a hotel room (Study 2) and that the next day they wake up in a room that is either quite dirty or very clean. Participants in the dirty room condition rated their susceptibility to STI higher, and had lower intentions to act the same way again. Results are discussed in terms of deductive processes, emotions, and magical contagion.