Again, pick your battles. My girls had to keep their room clean when they were in elementary school and some of middle school. It was a losing battle in high school. Kimmi's room probably has hazardous materials in it. When it came to their rooms, I figured if they wanted to live like pigs, I could just shut the door. They were not, however, allowed to let their mess go outside their own bedroom doors. Their bathroom had to be clean, and they had to keep their personal items out of the main living areas.
However, they are now grown, and both keep their apartments very clean.