Yep, I try to live up to my bargain and like GM's wife, I'll nicely remind others of theirs too.

Did you think less of your customer because of his/her comment? If the customer was paying would you have been comfortable in telling the customer to do the right thing?

Then there's my bank. You only get a "banking error in your favor" card in Monopoly. They'll get there's back without you bringing it to their attention. But, if they short change you, there's mounds of red tape. I have this anal habit of rounding off my deposit amount to a nice even number every week which results in getting $0.20 back with my cash. Sometimes I get the $0.20, sometimes I don't. If it's not in the little envelope, and I catch it before I leave, I'll ask for it. If I've gone outside the building or pulled away from the window, it's too late. If I went back in they'd say they have to shut everything down and count the drawer, etc.