TAMPA When the Mueller family sits for dinner, the leftover broccoli and crepes are already wrapped in plastic, the kitchen is beyond spotless, and the rest of the home is so tucked-away tidy it looks like they just moved in. In a way, they have: Every inch of furnishing, every little trinket and votive candle, sits precisely as designers placed it five months ago. That would make them the most perfect suburban ideal, except for one catch: This isn’t actually their home. Bob and Dareda Mueller and their three grown sons are, instead, part of an “elite group” of middle-class nomads who have agreed to an outlandish deal. They can live cheaply in this for-sale luxury home if it looks as if they never lived here at all.