Customer: Do you patch tubes?
Me: No we just replace them.
Customer: But the tube is in good shape it just has a hole in it.
Me: I understand sir but if that patch leaks you'll be back and you won't be happy so we just replace them, its better that way.
Customer: Well how much is that?
Me: 10 bucks.
Customer: 10 bucks, can't you just patch it?
Me: Yeah sure 15 bucks.

I only patch if I have to, I prefer to go the new tube route. Granted they do not cost me that much but whatever. I also have kevlar beaded tires on my bikes so if I do get a flat it tends to be a pretty good size hole like a large nail or industrial type staple which I would not trust a patch with.