Breeders clasify their puppies as either show/breeding quality or pet quality.
An experienced breeder spends a lot of time watching his litter as they develop and is able to pick out puppies that he feels have faults which would not justify the time and expense required for a show career or to be used in a breeding program. Often times these faults are very slight and unnoticeable to the untutored eye, and have nothing to do with the health, temperment or overall good looks of the dog. These puppies are sold as PETS rather than SHOW quality.
Reputable breeders either provide AKC non-breeding registration papers or require these puppies to be spayed or neutered before furnishing the AKC registration papers.
In order to improve the breed, breeding should be done from the best quality dogs; it is unnecessary to produce pets from pet quality dogs--plenty are produced from champions!
From "The Rottweiler: Learn Before You Buy," published by the Colonial Rottweiler Club.