I’d say to refuse to clean up any mess that you didn’t contribute to, but I don’t know how that’d go over, depending on your age. If you’re an adult, don’t take her crap. If you’re a teenager...at least you’ll be an adult in a few years?

This definitely makes sense, but the problem is her mom would probably just let the mess fester. Some people just aren’t bothered by mess. Like, imagine using a cup and leaving it on the counter or table for days. Shoes in the middle of the floor for people to trip over. Etc. Some people just don’t see it. And if the other person is more of a “neat freak” they’re forced to clean it up so they don’t go crazy. Sucks for OP. Maybe the docking allowance thing is a good option. “Mom, each day I have to clean up after you, I’m deducting $xx from your allowance.” I can’t see that going over too well either, though. And it sounds like OP has already tried talking to her. Maybe try again? It just sucks all around.