I have paperwork for my het pieds that I got from a "small" breeder. Even though he is a small breeder, I trust him and it makes me feel better knowing that he put his name and good word on paper.

The paperwork basically has a photo of the mother Pied and a photo of the snake I bought labeled as a het Pied.

Sure they could still lie and provide false paperwork, but that's where the buyer needs to protect themselves and do some research before making the purchase.