Back when Craigslist was still doing adult personals, I met quite a few women who were interested in doing anal with an older, married guy like myself. Invariably, the idea of ass to mouth was mentioned and always was tried. They liked it, much to my surprise, even if they were slightly dirty.
My wife always takes her lovers' cocks in her mouth after anal sex, for which she doesn't prepare specifically, and cleans them. And she does it with pleasure, especially when they are black men.