Is it out of bounds to consider plain and simple prejudice as the trigger?

Disgust reactions are frequently based on prejudices that should be challenged and rebutted. People frequently describe male sexuality in strikingly similar ways to how prejudiced people describe (typically male) homosexuality. You know, it's disgusting, it's ridiculous, it's wrong in some indescribable way, it's threatening and dangerous in some abstract, unfalsifiable sense. Except it's not taboo to talk about male heterosexuality that way. Men are pigs, after all, and that they want to have sex is ridiculous and wrong ipso facto. We should question and challenge rather than try to rationalize these impulses. Maybe the validity of this kind of reaction shouldn't be automatically assumed. Maybe the icky wrongness is hard to articulate because you're trying to implausibly rationalize a slippery gut reaction, not trying to describe an elusive actual moral principle.

Here's an interesting interview with Martha Nussbaum on related topics: http://www.reason.com/news/show/33316.html