Between clothing/sporting-goods stores and every house containing some (and sometimes a huge amount) of clothing, I’m not sure the zombie clothing really makes a significant impact.
That said, who wants to wear clothing that’s been hanging off of a rotting corpse and dragged through mud and other nastiness.
So the idea of putting disgusting, nasty items (of clothing, but potentially other items as well) into a separate category miiight not be a terrible idea.
Frankly you could just create ‘Ruined Shirt’ and ‘Ruined Jeans’ and whatnot, make them give much fewer rags. If you wear them it could give you the ‘Smelly’ trait and perhaps a negative mood modifier for wearing disgusting clothing.
I dunno, it’s not a terrible idea.