The problem with most breeders is that they are not trying to improve the breed, but just to make money. As a result, health and personality problems have become commonplace. and the intelligence of many breeds has suffered. Every time a movie comes out featuring a breed, there is an explosion of some horrible dogs due to reckless breeding. Mixed breed dogs are more likely to be intelligent, healthy, have a great personality, and enjoy good longevity than most purebreds.