Blindness and illiteracy abound. Here's an actual conversation I had with a lady:
SC: The copier charged my card 99 cents!
Me: Did you use the color copier?
Me: Which one did you use?
SC: That one. (points.)
Me: That's the color copier.
SC: Well, how was I supposed to know it was a color copier?
Me: Well, you see that big sign on the wall behind it that says "This color copier costs 99 cents per copy" ?
SC: No, I was just looking at the machine.
Me: Ah. There's a smaller sign that says the same thing on the lid.
SC: The lid was open.
Me: And one on the front as well.
SC: I didn't see those, either.
Me: Well, how about the little one on the card reader? Did you see that one?
At that point, I was doing my level best to grind her nose in her own stupidity as much as possible. She still had the balls to ask for a refund.