Not sure if this is beyond the scope of a stuff pack, but I always fantasized about a fashion system that allows us to tag clothing as either "in" or "out". Sims with a "Fashion savvy" reward trait (from satisfaction points, not taking up a trait slot in CAS) will react to the tags, but no other sim will do so.
Reactions could include moodlets, booing/cheering and modifiers to social interactions. A fashion savvy sim wearing something "out" should be embarassed or sad, a sim without the trait would not care. At the same time the fashion savvy sim would get a happy boost just for being in the vicinity of a sim with "in" clothing and get sad or angry at seeing a "wrongly" dressed sims.
But all of that should be in our hands. If I want cc elf ears and kitchen aprons to register as fashinable in my game, I should be able to do so.
Another tag could be "branded". Branded clothing is exactly the same clothing we choose in CAS, but with an invisible label that only Snobs, Fashion Savvy sims and Materialistic sims can see. They react favorably to brand clothing. I do not know how that could work ingame, sadly. Maybe a token that sims can carry around in their inventory and that is keyed to an outfit and a category.
Example: Bella and Summer both wear the same outfit that I assigned them in CAS. But Bella carries a brand token that is keyed to "Everyday Outfit 2". Whenever she wears everyday outfit 2, fashion savvy, materialistic and snob sims like her better. If outfit 2 is ever modified, the token expires and new one must be bought.