I understand just what you are saying. I finally bought a large trash can (one you use outside) and put in in the hallway. Told them if they wanted to keep their crap then it better not be left on the floor. They didn't believe me, so after they went off to school, I cleaned house! anything and every thing that was on the floor went into the trash can ready for the dump. When they got home they were so surprised to see how clean their rooms were. But when they opened their draws and closet (Knowing mom had put things away for them) the shock hit they like a ton of bricks. From that point on, house rules were, if you like it you better put it up or it goes to the dump, no exceptions!
Oh yea I forget this happened one year 2 days after Christmas so all the stuff they had gotten for Christmas, well it went to the dump as far as they knew but since this was brand new stuff I gave it to good will. I know there was some child out there that would take better care of it.