An evening at the Mercury Lounge often proves a real treat. The structure of their shows almost always includes four bands with a time slot of roughly an hour per act. In essence, the evening feels exactly like your run-of-the-mill showcase night a la Arlene’s Grocery. You know, the neighborhood venue trying to reel in a few patrons without giving away drink specials by offering up the stage to wet-behind-the-ears bands playing in front of their poor friends who were given no option but to drop