Inbreeding may result in a far higher expression of deleterious (In the biological and medical sciences, deleterious means something harmful, such as:

Natural selection works to remove individuals who acquire the above types of traits from the gene pool, therefore many more, in the first generation of inbreeding, will never live to reproduce. In biology, the fittest are those who survive and breed. Over time, with isolation such as a population bottleneck, caused by purposeful (assortative) breeding or natural environmental stresses, the deleterious inherited traits are culled.) Many working breeds are bred for appearance rather than working ability. People who have not considered these factors often stint their breeding stock in terms of veterinary care and adequate maintenance. The puppies they produce may have genetic disorders or undisclosed illnesses, but will often try to sell their stock before they become evident to buyers. They rarely screen potential buyers or inform them on breeds whose care and maintenance may be inappropriate for their lifestyle.

When such breeding is carried out on a large scale, the venue is called a PUPPY MILL (especially in North America) or puppy farm.

Other categories of backyard breeders noted by dog clubs include parents who wish to breed animals so that their children can experience the process. These people may not be motivated by profit but have not adequately considered that they may be adding to the population of unhealthy or unwanted dogs. Backyard breeding is also blamed for the proliferation of aggressive dogs for the usually illegal sports of baiting and dog fighting, and to defend venues of criminal activity. Aggressive dogs are also important to the macho image of men in some segments of society. Dog fanciers generally believe that such ill-bred dogs are the reason for the bad reputation of some breeds in the public perception, and the resulting breed-specific legislation.

Remember...if the price is too good to be true...there's something wrong.