I scrutinize even warranty dealer work. I almost always have to tell them about something they should have done. I bring my binoculars to the big shops. I know I'm not their favorite car owner, but, I make sure things get done correctly. Just the last time, I had them put it back up on the lift, because the tech forgot to rotate the tires...then I had him go back and adjust the tire pressure, because while he did do that, he did it before the rotation, and the front and rear take different pressures. A small thing, and the service is "free", but, I demand it be done right.