Items that have the FANCY flag (but not SUPER_FANCY, that works correctly) but don’t occupy a body part (like ties and jewellery) don’t give a morale bonus when worn with the stylish trait.
Way I understand the trait, it’s designed to encourage folks to wear Less-Practical Gear. FANCY gives a bonus based on what it’s covering, and SUPER_FANCY gives the location-based and then an additional +2 (which is why you’re seeing it when it doesn’t cover anything).
So the question is, how Stylish is just slapping on lots of bling? I could certainly whip up a patch, but would you accept 0.5 morale for brooches, rings, etc?