I had a problem with a large appliance. Guy came and looked at it and recommended a course of action that was free and I took it. The problem came back after a month. When he found out his advice didn’t hold, he came immediately to perform a repair because, as he put it, he didn’t want his reputation to be damaged in my eyes.

He offered what he thought was best. When that wasn’t it, he wasted no time getting to the next step. I tipped him more than I otherwise would because his concern over getting it right seemed genuine, and I care more about that than I do getting it right the first time without really caring one way or the other.