I have 2 teenage DS.
Eldest has always been relatively tidy as in puts clean laundry away (though usually has a chair covered in discarded items), usually makes his bed, puts rubbish in his bin, doesn't accumulate too much crockery etc. His room is a bit dusty but if you give it a cursory glance it looks ok, and generally he's been pretty good keeping it like this since mid teens.
DS2 (17) however is another story. His room is indescribable. Last year I redecorated it and got him new carpet. But now it looks awful. He doesn't like me to go in. When I do there is stuff everywhere. He doesn't bother changing bedlinen, chucks rubbish on the floor, with all his clothes and everything else. I would gladly help him tidy it, but he refuses. At the moment it's so bad he won't even let me in the door. Aside from this he is doing brilliantly at college, will help round the house and garden when asked, but the room is driving me crazy. He only ever goes out to college but that's when I'm at work. So I can't get in the room when he's not there. Although part of me feels I shouldn't go in if he's asked me not to.
So do I just ignore it and let him get on with It? Or if not do I just go in and clean overriding his objections? He does say he will sort it out next week once he finishes college for the year but he did previously sat he'd sort it out in half term and that never happened.