Honestly this is what had been bugging me about morph breeding [especially "Super" types] for a long time; I still don't think I'd be comfortable purposely inbreeding/linebreeding if I had my own, maybe I'm weird ^^;
I do recall, a few years ago, stumbling onto a GTP or Emerald Boa breeder's webpage back when I was reading up on snakes, and they had a lot of hatchlings for sale that were missing one or both eyes, which I thought was caused by inbreeding so that was a huge turn-off for me ._.
Thanks for this thread and all the informative replies, I understand a bit more about this sort of issue now :3