I wouldn't "make sure they aren't bred" I let the people know they are pet quality, if they decide to breed on their own that is their mistake. (IE...go to any humane society). But, I believe by putting it out there that you feel some animals are below breeding standards, a lot of new breeders would see that and think twice about it.
Noobs come here and just see the numbers (money). I doubt they'd care that much if you tell them the snake is low quality. Idk, i could be wrong though.