anything can be faked.
it comes down to the word of the breeder.
but you should get a picture of the snake and of both parent snakes. pictures of siblings and information on the genetics of the grandparents is also nice to have. that all helps to see what genetics went into the snake and helps to avoid inbreeding.
but in the end, you just have to trust that the breeder is honest. Breeders with a good reputation can back up what they say with their good reputation, but thats all. After a few breeding seasons someone can have a huge quantity of unpublished pictures showing lockups, eggs, snakes on eggs, snakes hatching from eggs, enough material to forge photo documentation.
but then, most breeders are honest and take it seriously. Reputable breeders just dont lie about their snakes. Breeders provide snakes to other breeders, if someone makes stuff up it will be found out when other breeders actually breed these snakes. So you have something like a network of mutual trust among breeders.
When other people that have done business with breeder XY say you can trust breeder XY, then i trust breeder XY and thats it. Pictures are nice, but i think judging breeders by their reputation is actually more reliable.