Zombies are cheap. They have no need for new clothes! Seriously it’s not like they have modesty or anything. To them the more blood on the clothing the better. It’s like a badge. For kills. Kinda like painting a kill on the side of a fighter.
Also do ya think they’d need the newest cross trainers? They have NO feeling in their feet! Comfort is not an issue for a zombie. Only YOUR discomfort matters to them!