I have decided to focus on what I like and not whats the latest trend. That way if they are not good breeders I have pets I love and will keep regardless.
For me its Bels and most of the albino types. (with a few other morphs to enhance them) Oh I love normals too.
I think going for snakes that would make good pets and are pretty, breeding for temperament too and not just the latest trend (trends change) helps.
I never sold to pet shops. I also only sell to people who can prove they know what they are doing or have done their research which shows commitment.
Beyond that I don't know. I am not sure there are any guarantees.
Your point is of concern to me too. Do you have any advice?