Frustrated!!!

I have two roommates and one of them is an absolute slob!!! I do not understand how you can live in a an extremely nice apartment and want to trash it out! My other roommate and I always clean up after her and want the place to look nice, but she just goes behind us and makes it filthy again. I don't know what to do anymore because I want to yell and shout at her and tell her that if she can't clean up after herself at 21 years old then she should not touch anything at all. Just eat out and DO NOT COOK ANYTHING!!! >:-/