Anything that involves licking human skin will just feel like you're sucking on your own thumb. I'm unsure on why would anyone find anal "oral" sex somewhat satisfying (when not being on the receiver's end), so I suppose they do it for the sake of satisfying its partner and nothing else. As for me, I wouldn't really like getting my butthole licked by someone else because I do find it gross since, you know, I don't really have to restate the obvious for none of you folks.