Even better are those that think their "designer" mutt is papered. Those are the ones I always write to and ask who the dog is registered with :-)
No matter what anyone thinks, if the dog in not an established breed (either AKC or UKC) it is just a mutt. Anyone who pays a lot of money for a mutt is just not thinking. I spend 3 hrs every Friday at the local Humane Society and see so many nice dogs getting homes. It's a wonder that people still think they're getting something special