Wow - you’d step in and demand action way before it got to this stage surely.
Some of the little kids rooms, I think some of it is down to no storage (visible) in the room, so where do the toys go? Plus too many toys and clothes, which is the parents fault. Don’t buy what you don’t have space for!
The ones with rubbish etc are just horrific and I don’t understand why you would allow a your teenager to let their room get even halfway that bad before you did something.