Depends on the girl. If she is hot, has a beautiful ass, is ultra clean and showered before bed, and is the kind of girl where you can't even remember the last time she farted, go for it.
The whole bacteria thing is a bit of a myth. If the girl is freshly showered and has good hygene, there is no bacteria on the OUTSIDE (the part you are licking).
Its been my experience that more times than not if you lick a girl's ass for a couple minutes she is going to quickly agree to having you poke something larger in there.
