I like to see a breeder who goes out of their way to make sure that the customer gets exactly what they want. A good breeder responds to emails and calls within 48 hours (not always possible, but should be what happens most of the time) a good breeder is willing to answer husbandry related questions as well as questions about the snake and it's lineage.

Less important, but I like to see breeders who are active in the reptile community, who take the time to share some of their knowledge.