Using self-report, this paper explored whether a malodour's source (self, liked person, stranger) influences hedonic responding. In Study 1, participants were presented with vignettes describing various encounters with malodours. Negative affect increased when body malodours emanated from a stranger rather than oneself (the source effect). Study 2 replicated this finding using a smell diary, in which participants recorded their hedonic responses to real odours. Study 3 determined that this source effect was not due to a social status or a halo effect. Study 4 examined the role of exposure and attachment. Exposure, but not attachment, best accounted for the source effect. Study 5 examined whether perceived disease risk varied by source and whether this could account for the source effect The findings suggested that there are two mechanisms by which disgust responses to malodours can be modulated to reflect the disease risk of their source: implicitly, by mere exposure, and explicitly, by knowledge of risk. In the discussion, we argue that avoiding contact with disease-causing agents is adaptive, and that this is implicitly modulated by exposure, so that the cues for disease emanating from people encountered less frequently are treated with more caution.