Meh. I’ve had to wipe that area of a few dogs, horses, and some others, but it’s super rare.* The tail is held up and away from the anus while the fecal matter is pushed out, so the dirty portions don’t touch the ‘clean’ areas of the tail and body… and I would bet if we had tails we would do the same and keep the tail held up until we’ve finished wiping/bideting. The animals also can keep it up and out of the way for the duration of sexy times, so I would bet we’d have no issue for doing it for the few minutes between evacuation and cleaning, and that’s before even considering that we’re human and could build a tool/device to do that already.

*Only exception I can think of immediately is pretty gross though: Cows are hideously unclean on average, with their shitty bumholes spilling over the vagina, balls, and tail if the owner doesn’t clean them occasionally. (The colon health / fecal composition is pretty dependent on the local conditions and feedings, so it’s not like they’re always bad)