You must also take into consideration, snakes are not migratory animals. Therefore, inbreeding is very common even in nature. It will take more generations than we could count before we should see negative effects.

In my opinion, the problems associated with Caramels, Spiders, Cinny/Black Pastels are not from inbreeding, but are problems with the gene itself. In some cases new phenotypes evolve from inbreeding in nature.