This article addresses two topics related to disgust in the philosophy of Friedrich Nietzsche: (1) how moral disgust is harmful and (2) to what extent moral disgust is conditionally fitting. Nietzsche argues that self-disgust is dangerous because it is characteristic of ascetic morality. Yet disgust is conditionally fitting insofar as it triggers an adverse reaction to ascetic moral systems, or what I have called “disgusting moralities.” The first section is a general analysis of the role of self-disgust in the cultivation of ascetic morality. In the second section, I compare this analysis of disgust to two popular contemporary theories of disgust (the Terror Management and Animal-Nature Reminder theories). In the third section, I argue that Nietzsche advocates disgust at certain harmful moral systems. He thinks disgust is a fitting emotion for such moral systems because it causes an immediate adverse reaction. This reaction is fitting, Nietzsche thinks, because such moral systems are infectious. I maintain his view of disgust is compatible with convincing psychological theories of disgust, namely the Entanglement Thesis and Co-Opt Thesis.