Patrick,
the question you pose is indeed one that I have had defintie opinions on for a long time. To answer your question simply yes "in-breeding" as defined by breeding siblings or related animals to each other to get a desired result is indeed a normal practice when dealing with any morph, color phase or specific pattern. The reason for this is that in order to produce albino's for instance many times it all starts with only one animal, that animal lets say is a male and he will be bred to several unrelated females. Then those offspring are bred back as "hets" for the albino trait to produce a percentage of albinos in the first clutch.
Those albinos are all at least partially related animals. Normally there is not a probelm on that level, but on subsequent levels if the genetic pool is not broadened it came become a problem in my opinion. A perfect example is the bulbous eyes of the Leucistic Texas Rat. Or the fertility problem with albino ruthveni. In-breeding while very helpful, accentuates the good and sometimes the bad in a certain line and enhances the possibility of certain birth defects.
With all that negative stuff said though realize that in the wild a certain amount of in-breeding occurs on a natural basis as most snakes travel very little during the course of thier entire life. Thereby the chance for a sibling or a parent breeding with a related animal does and will continue to happen. this is the reason some locale animals all have a certain look from a specific small area. But there is enough genetic diversity within those small locales to produce healthy and viable animals for many years in most cases.
So is it bad to in-breed for color, locale, pattern or morph? In my opinion no it is not a problem as long as you keep good records and out breed to wild caught or completely unrelated aniamls every 3rd or forth generation to bring new bloodlines into your genetic pool. For instance we have been producing Leucistic Texas Rats for about 15 years now and have gone out and produced hets from wild caught females every third or forth generation thereby our line of Leucistic Texas Rats have no bulbous eyes.
Remember though when you are producing these animals in captivity the genetic pool is limited by the number of animals that are avalible to you for breeding, so every once in a while you will either have to have a new animal brought in, swap with a friend for the breeding season or have a fairly large group in your own collection. Our breeding groups are maintained on a ratio of 3.7 of unrelated animals if at all possible for instance.
In the pits. we produce many color and pattern morphs each year and they are just as viable as the normals we produce. Eating, growing and finally breeding at normal ages and sizes.
Bottm line, buy your color morphs, locale specific and pattern morphs from a good breeder large or small that keeps good records and you will be fine. The best part of the deal is that MOST pit. keepers are dedicated to the premise of keeping the lines pure and healthy unlike some of the other potions of the hobby, we tend to be almost radical about it.
I hope that answers you question, if I can be of futher help let me know.
John Cherry
Cherryville Farms

Cherryville Farms - Reptiles