If you go to the book by Winifred Strickland and Jimmy Moses, the best way to get a champion is out of a champion, and you breed a daughter back to her champion father. But they are all about culling too. They aren't talking about fixing them and selling them on a limited basis to pet homes, either. They say it is one thing to cull puppies that are off color or weak (I am paraphrasing) but when the puppies are equal in quality, and you need to cull some that is hard.
Breeding sire to daughter, mother to son, will not create temperament or issues. But because there are recessive genes present and the pups will have double, you are going to get some of whatever is back there out. So if you want to know if your dog carries the gene for long coats, or something you might do a test litter.
Know you cannot just know on some of this stuff. Some of the genetics are cut and dried, some are less so: if you breed an affected dog to an affected dog, you will get so many affected, so many carriers, if you breed an affected dog to a carrier, so many affected, so many carriers, some unaffected, if you breed an affected dog to a non affected dog, so many carriers, so many non-affected -- whatever. It is easy to see if a dog is affected, but the only way to know if a dog is a carrier is to breed it back to a known carrier or affected dog. That would be a test breeding.
It does not have to be something nasty, it could be long coats, or black color, and other stuff.
As for incest, that is applying human moral/religious/societal codes to animals. There is nothing disgusting or horrifying about it, because dogs do not have the moral codes programmed into them. For humans it makes sense, continued in breeding will reduce the gene pool and cause a degradation in health etc. And for the protection of children and families it was necessary to have a taboo on close family relations. But animals are simply not covered under this code, though in general breeders want to be conscience of pedigrees so that they do not breed generation after generation of close inbreeding.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC