IMO it's one good argument for having multiple hides, and enough space to put them. If there's a choice of hides in each temperature zone, the snake can pee or poop in one and still have a clean one at whatever temperature it wants. Also a good argument for loose substrate instead of paper towels, since paper towels will make the pee spread out into a giant puddle. If the snake is in a small-ish tub with one or two hides and a paper towel, then OF COURSE it will end up sitting in a puddle of piss when nature calls. If it has more space with a variety of good hides, maybe it will still end up sitting in the puddle occasionally... but probably not nearly as often.

Of course you should still clean it up when you see it, but it could easily be many hours before that happens.