I know a lot of posters are dealing with big issues at the moment. This is a relatively small one. (despite the over-long post!)
My DSCs are 15 and 17. DH and I have taken the view that the kids' rooms are their own business, basically. When we all moved in together and put together 'house rules', I said that I did not want food/dishes left in the rooms; and the rooms could not be a fire hazard.
I have insisted on the rest of the house being kept tidy. The DSCs (and toddler DD) are expected to clear away anything they've left in the comon areas of the house, every evening. We have a jobs rota: the DSCs help with dinner and washing up; they get a generous allowance, part of which is linked to doing their chores. The rest of the housecleaning falls to me and DH; we almost never 'just ask' the DSCs to hoover the front room - they do their assigned chores and that's it, really. DSD will occasionally mow the lawn.
The bedrooms are, therefore, messy to say the least. They never make their beds, clothes are piled up rather than put away in wardrobes and drawers, things are just left on the floor. DSD's isn't a problem, as far as I am concerned, because although it is very untidy, it is not completely overrun, there are seldom dishes or empty food wrappers, and it gets tidied and hoovered when she has a sleepover (a few times a year, I guess). DSS's room, though, is disgusting. About once a week I go in and take out the dirty cups and mugs. (In general, I don't enter the kids' rooms, though.) He leaves sweet packets, crisp packets, coke bottles all over the place. His desk is so covered with trash and papers that he can only use a corner of it, and I think it does affect his ability to focus when he is doing his schoolwork. His clothing is strewn about or in a pile at the bottom of the wardrobe. He has a hard time finding things, and is quite disorganised and loses focus frequently when trying to do any task.
Anyway. I know that everyone says their teenage boys' rooms are a mess, but I admit that I wonder if this is just over the top. Also, even if "it is just normal teenage behaviour", is it normal for us to let it go?
In the past, Dh or I has offered to help him clean, maybe once a year. In reality this means DH and I doing most of the work. DH asked me if I thought we should give his room a clean again - but I think 15 is too old. It was fine at 8 or 9 to be cleaning his room for him... Perspective, please?