Ack, apologies again if I devolve into a ranting mess. Probably shouldn't comment on these types of topics but I feel very strongly towards them.
I have to agree with Scutellatus's statement. Just about every Tom, Dick, and Harry are "line-breeding" their reptiles simply for the chance to create something different that will fetch a higher price. But Yellowtail's right, inbreeding can be common in certain wild populations. If a weak specimen is produced from such a pairing, however, mother nature has no qualms snuffing it out. People on the other hand tend to horde such things. Even using the weak animal extensively in their breeding projects because in many cases that particular specimen is the most unusual. This is when line-breeding becomes a problem. That, and when people refuse to out-cross every now and then.
I call it designer breeding when people breed explicitly for the purpose of enhancing or creating a particular trait specifically to appeal to the masses. It doesn't have to be restricted to breeding hybrids. I would also include it to people that breed animals of two distinct localities together. I remember on Facebook where someone was inquiring what cool and weird colours they could produce by breeding two locality specific lizards together, two distinctly different animals of which I would not be surprised if they were allocated subspecies status sometime in the future. It makes me wonder - why? Both lizards are equally beautiful in their own right so why would you want to change it? Although I won't deny that some selectively bred animals are stunning.
But it seems these days that more and more people are selectively breeding for some trait or another in their all important goal to prove that they can do better than mother nature. That does seem to be the common practice these days in the reptile keeping hobby - paint-jobs, paint-jobs, paint-jobs, developing distinct lines like pedigreed dogs etc. etc. Sometimes I wonder if I even follow the same hobby. I don't really care much for the paint jobs and the hets for this and hets for that, I'm interested in their natural forms and behaviours. Why don't we keep the practice of breeding extensively line-bred bizarre mutant creatures far removed from their wild ancestors to dogs for goodness sake? As that's where I see the hobby is going.