Skiploder posted a discussion about what constitutes inbreeding not long ago --> http://ball-pythons.net/forums/showt...tes-Inbreeding
It's worth pointing out that most of the mutations we have in the trade are all descended from a single individual (ie. all pinstripes are descended from one snake). To get supers, you simply have to breed snakes that are related in some way. Are there issues that arise? Kind of, but they aren't all that common and tend to be attached to mutations that were never without the issue (the wobble in spiders, womas, and champagnes; the kinking and duckbilling in super cinnamons; bug eyes in super lessers, etc.). Random birth defects do occur, such as small or missing eyes, but they're very rare from what I understand and I'm not even sure if those defects can be linked to inbreeding.
Most people line breed without much thought, from what I've been able to gather.