ask them if they test-road the bike after working on it?......my LBS test rides Every bike they work on, even if it's just basic maintainence!
(they always wait for me to get there to test ride so I can giggle with them when their big, hulking, sweet mechanic rides my little 50 cm frame!)
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"