Yeah often you aren't allowed to put anything on the walls of a rented property, even bluetacked posters!Since he’s renting, it is likely he’s not allowed to paint walls, and may well be restrictions on nails in the walls and that sort of thing.
Probably why he doesn't have much scope to put art up or repaint. Doesn't stop him from having absolutely zero taste when he does try though...
He has no sense of individualism AT ALL.