OP, in my experience, this can be another one of those regional things we often talk about here. I'd pay attention to the brands his peers are wearing. He probably knows what brands the cool kids wear. FWIW, I'm not saying your DS isn't one of the cool kids. I'm just using that word, because you did.
This is true, I wash and fold so many items I don’t recognize, from boyfriends, their friends, their friends boyfriends... With three girls and two boys, it drives me crazy, especially for items no one can identify. My sons lose their winter coat every year, plus sweatshirts.
Exactly this - I always wonder if the boy's moms mind that they are essentially buying clothes for other kids. At least with her girlfriends they usually Swap clothes so it seems slightly more equal. But the poor boys must never have any hoodies for themselves to wear.
OT, but these posts made me laugh. We went through that with DS. He was constantly losing his & accumulating other's clothes. It was especially frustrating, when I would look for a specific outfit for him to wear to an event & discover the shirt, pants or both no longer lived at our house. He wouldn't have a clue which friend had them. They did the same with shoes. I didn't really have to worry about girls stealing his jackets or hoodies, because there's not much of a need for outerwear here. If there were, I have no doubt his would have disappeared. Growing up in NC, I was guilty of taking home a couple letter jackets, before the boys' parents even got to see them.

Being the considerate person I am, I made sure to show them how nice it was, when I saw them at a game.
On a similar note, I've had a lot of random dishes, silverware & cups from girl's houses live here temporarily, until they were carried off & left at another most likely temporary home. Not to worry, their parent's tableware has been replenished with my once matching sets.

DS is now living with us to go to grad school & it's gotten worse than it was in high school. We're constantly having to replace stuff he's carried off & not returned. I told DH I was going to restock everything as cheaply as possible, until he moves out for good, then I'll purchase the same quality I once had.