As the purpose of conformation shows is to assist breeders in the selection of breeding stock by rewarding with championships the dogs which, through external observation only, are the best representatives of the breed, major faults or an excess of minor faults would prevent a dog from completing a championship and being bred.
"[2] Another major fault would be visible structural problems of the dog that prevent the animal from doing the type of work for which it was bred.
A level bite, an under-bite or an overbite may be considered faults, depending on the breed standard description.
Sometimes these colours change over time, often after much in-fighting and bitterness.For many years, the only acceptable coat pattern in a Dalmatian was white with black spots, very recently liver spots have been accepted as a variant, but black still appears to be the preference of most.
A black German Shepherd Dog is penalized; a white GSD is disqualified, as the color is believed to be linked to deafness and other serious health problems.
In the future, genetic testing may show which of these variants in color are actually linked to health problems and which are not, which may lead to modification of the breed standards.
The breed standards for working dogs usually specify that scars, broken teeth or other damage that evidence injuries sustained during a working career (often termed ‘honourable scars and injuries') are not to be penalized in conformation showing.
The Australian Cattle Dog is an example of this as are some terriers, where the breed standards specifically state that scars are not to be penalized as faults in conformation.
However, even in the JRTCA breed standard only externally observed aspects of the dog are described, as working tests and genetic tests are beyond the scope of a breed standard, which exists as a description of the dog, not its DNA.