More precisely, only the ones that can be picked by just left-clicking at them (not the ones that require a "pick" action), at least according to my tests.
All you need to trigger this bug is...having your inventory full.
As long as the item isn't put in the inventory, its true quality is displayed. It gets properly capped once you put it in the inventory, obviously (else i would have pmed it to jorb directly without making a thread ).