For four years I had a housemate who was an incredible slob in his room. There was stuff all over the floor with barely a path to his bedroom. Did I ever say anything to him about that? No! That was his room to do with as he pleased. He was perfectly neat in the kitchen and other common rooms in the house.
The room that belongs to one person, that they pay rent for, is their own space. Everyone has a right to being left alone in their own space, assuming that their habits don’t make a problem outside of the room.
