Papers are only as good as the breeder is.
Any shady breeder can produce paperwork, if they are really shady it won't matter, they will not stand behind their animals and will have long disappeared before you have a problem, paperwork or not, binding contract or not.
Many breeders do not provide any paperwork with their snake and I have no issue with that, it's all about buying from someone reputable to me.
I still provide paperwork but it's more in the event of a re-sell, I want to make it easier for my customers to be able to re-sell their animals, giving the ability to the future next owner to know where the animal originally came from and to contact me if they have any doubt on the animal being offered to them which is I keep pictures and original paperwork on ALL animals I have ever produced an sold.
As for animals that I purchased without paperwork, I will only sell them and guarantee their genetics if I prove them out myself.