The most overrated MAC l/s, IMO, is Hug Me. It is so not wearable for this NC 15/20ish, dark hair & eyed girl. I don't know if it's my pigmented lips or what, but this has always, always looked awful on me!
I know it's different for everyone, but my underrated fave is Lovelorn. It's a great pink that I hardly hear anything about!