Not that if they had such an accident they would record it.
Yeah, I should clarify that. By "clean itself" I don't mean "wow, it's so clean in here — I'd eat off the floor" clean. I mean clean for the inside of a butt. I was talking about heroic measures, high colonics and suchlike, and the way hosing out your innards on a regular basis cannot possibly be a good idea.
There is, sadly, no way to guarantee that you will never see "something" again (but you might mind it less if you were using a condom, hint hint). Word has it that the pros do douche the night before. That requires a certain amount of planning, which is easy to accomplish if you know you're going to be having anal sex from, say, 2 to 3:30 p.m., and never on Wednesdays. If you can pull that off, more power to you.