H.S.
My son is leaving all his stuff around too and I don't like it either. But there is only so much nagging I can do.
I don't like the throwing away idea, because if if throw out the one pair of sneakers he has, do you end up buying new ones, since he needs them for the gym? I also don't think it instills a good value system, if you just throw out stuff.
I have been hiding things on occasion, but that seems so silly in the long run.
As for adding chores, which seems like a sensible punishment, I wonder how you get a child to clean the bathroom, if he/she doesn't even do other basic things?
I like the idea of "everybody cleans up together" and have in the past set the timer for my son to clean up his room ("spend 15 minutes cleaning up"). Often I think he is just overwhelmed with everything that the job looks just way too big - and probably is!
I hate the "in a minute" and won't let him get away with it anymore. When I hear that, I only respond "now", and he does it.
But what bothers me most is that I have to micromanage him, and I wish there was a quick fix to that. But I guess part of this is his personality and part is me.