This is something I majorly struggle with, living with my partner's 16yo son. He just doesn't tidy anything up, sheds belongings as he walks round the house. He drinks squash and he's the only one who drinks it, and will leave the empty bottle by the sink, despite the fact he has to walk past the bin to leave the room.
There's so much rubbish and crap in his room that it comes out onto the landing when he walks out of his door (I just kick it back in). He wears ALL of his clothes before he puts ANY in the wash. Never tells me he's put EVERYTHING in the wash, and then comes to me late at night and says "can you wash X, Y and Z before tomorrow? I've got no clothes to wear" if he just put things in the wash as he took them off, he'd have a steady stream of things to wear. But what can I do? I refused once to try and teach him not to do it, so he went to his nan's in shorts in December, and I got a snotty phonecall about not looking after him properly. He'll keep towels in his room after a shower, so I'll go into the airing cupboard when I need a shower to find they're all gone (I will use my towel a couple of times so he's had chance to use loads before I need one), as he has two showers a day with a fresh towel for each.
He will take food out of the kitchen all the time, in addition to meals, but then keep the plates upstairs, leaving us short when it comes to mealtimes. He has been known to put empty egg boxes and other containers back into the fridge instead of the bin.
My partner has said he can't have his pocket money each week unless his room is tidy, everything is in the wash, and he's been bringing his plates down.. but he honestly doesn't care, as his mum gives him £40 a week (!!) as she's on a fantastic wage, so our £10 a week means nothing to him, and isn't worth the effort. Plus, they have a cleaner at her house, so he gets absolutely everything done for him there. He sees her every other weekend btw as my partner has custody.
Sorry for the rant there.
Anything he leaves around the rest of the house gets put in his room when I go upstairs, my partner and I keep the rest of the house clean, but refuse to clean his room. That's one thing he should definitely do for himself. It's not even hard. He is always either doing his homework or on his PlayStation, so how it turns into a bomb site I just don't know. I don't think it's unreasonable to ask for dirty clothes to go in the wash, packets and wrappers to go in the bin, and plates to come downstairs.
I WFH, incredibly long hours, and would just really really like it if he could take responsibility for his own mess, and make things a teensy bit easier for me sometimes. I just don't know what to do. He doesn't get his pocket money and doesn't care. He doesn't care about anything we punish him with. He just won't be tidy.
I wouldn't mind as much if it didn't impact the rest of us, but the washing thing and the dishes thing, and the towels, and the mess outside of his bedroom, are honestly issues on a daily basis, and issues I could really do without.