Customer: This magnet you made me doesn't stick to my truck's left side.
Me: Okay, I don't understand why, it's the best magnet material available and we've never had a complaint before. Let's check it out.
We go out to his truck. He puts the magnet on the hood of his car and says, "See, it sticks to the hood but not the side".
Me: Sooooooo, that leads me to believe it's not a problem with the magnet. Has your truck ever been in an accident on that left side? Could there be bondo there?
Customer: Yes the truck was in an accident, but there is no bondo there.
I then take the magnet and it sticks to every other part of his truck except that left side.
Customer: Well, I can't use this magnet because it won't stick.
Me: (in the spirit of customer service) If it you want, we will give you a refund.
Customer: Okay, thanks. And I'll be back to order some signs from you guys.
Hasn't been back since. So, it's a win-win situation - he left happy and we're glad we paid him to go away.