I also tried the method of picking everything up and putting it in a basket in the hall outside of their rooms. First, noone bothered to look at what was in that basket. Then when they were looking for something I would suggest they look in the basket. After a few days the basket still sat there. Apparently they didn't NEED any of that stuff. ???
I guess I need to put my foot down!
DDs used to leave the bathroom in a mess of makeup and hair appliances. I couldn't get through to them the importance of putting their stuff away so I began to inconvenience them by putting things away in different places each time. LOL They were not happy at all! They are better now, but it didn't CURE them. DH thought I should throw everything in the garbage, but I couldn't bring myself to do that.
And don't get me started on damp towels!!