Another hole in the wall like Mabel's on Main. What they also share is the cool, dim lit interior, great music, wonderful service, and a nice clique of beautiful and sophisticated people - fewer of the average Scottsdale douchebags, which suits me just fine. (They're in Spanish Fly on Sat/Sun afternoons - quite a sight!). Recommend Merc almost as much as I love Mabel's.
Why not 5... place was empty of a Saturday night. Go figure for such a gem!