All breeders have their favored characteristics and pet peeves. All are willing to sacrifice the perfection of certain traits to consistently achieve others they feel more important. This "worldview" on their chosen breed(s) leads to a style and the emphasis of certain traits within the correct type that breeder will be known for (e.g. size, headtype, longevity etc.). That many breeders have deliberate styles of dogs is good for the breed; it preserves the variety & strength of the breed. But many breeders fall foul of their own likes & dislikes, especially at the beginning when they know little about the breed and later on, as the years pass and they achieve some success, having now looked at the style they chose to breed so long they think of it often as the breed itself. If this quality is combined with an intolerance for one's rivals and/or for the faults least liked and virtues most admired, a good line of dogs will dwindle down to be more memory & reputation than a still truly vital line producing excellent dogs. Kennel blindness is also an almost universal trait of the "Sour Grapes Society;" those "wannabees" in a breed who have a thousand excuses for why their dogs don't succeed, all of them to due with the faults of other people and other people's dogs. It is also a major trait in so-called "pet breeders" who tend to not self-educate about the breed at all, so don't really know much about the breed they may well adore. They generally let their love for their pets blind them to their breeding worth...or lack thereof.