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Headcanon - supernatural - Dean
For me Dean is a housekeeping freak, he always tidied up the hotel rooms when they left the room, he always tidied up behind Sam, he always tidied up behind his father. He's used to it.
When Dad was on a hunting trip and Sammy was sleeping, Dean cleans up. He has nothing else to do, he can't sleep, he has to watch Sammy ¯\_(ツ)_/¯
Now it has become one of his habits. Especially when he's stressed (so often :/) he likes to be in a tidy and clean place, that's just how he is.
Sam is rather a messy person, but only in his room because Mommy Bear Dean is coming for him otherwise. But in general, Sam is really clean. I mean he's lived with Dean all his life.
So yeah, In my opinion the bunker is always very clean🧹
Headcannon that when Jason was still Robin and in teenage rebellion phases, Bruce bought him a studio with blank walls like canvases and let him do whatever. He'd buy Jason Spraypaints and supplies for his birthdays or just whenever he needed them. After Jason came back from the dead, the studio became his "HQ". Though he didn't like Batman, he had to admit that he did one good thing in his childhood.