My room is small with minimal storage and gets claustrophobic when it's messy. That's not to say I keep it as tidy as I'd like, but I do prefer being there when I've just cleaned. But I think the main part of my discomfort when my living space is messy is worrying that someone will come in and I'll be embarrassed. Or if it's a shared space, frustration and anxiety over division of household labour/perceived inconsiderate...ness. (...My parents are good people but they have some issues surrounding the things above and they're also proto-hoarders. I've been training myself to just get rid of stuff, it's fine, so I think clutter has become more irritating to me than it used to be.) So it's not really the fact that the room is messy that upsets me, it's the social-relationship-tension that it evokes in my head.