Mixed breed dogs (aka mutts) tend to have a lower risk of hereditary diseases than purebred dogs. Even when breeders make efforts to remove dogs with heritable medical problems from their breeding pools, some conditions will get by undetected in earlier generations. Hereditary problems are very common at puppy mills or with irresponsible breeders, as breeding stock is not selected based on any health criteria.
The temperament of a mutt can be just as solid as a purebred. While some breeds do have behavioral tendencies related to their breeding (for example, herding behavior in dogs bred for that purpose), there are no guarantees that a purebred dog will follow that tendency. The reality is that every dog is an individual.
America has a long history of affection for mutts. Two of the cinema’s most famous dogs — Spike from “Old Yeller” and Higgins from “Benji” — were mutts adopted from shelters. Heroic mutts such as Balto, the sled dog who brought lifesaving diphtheria medication to remote corners of Alaska, are immortalized in bronze statue form. Even the currently fashionable “doodles” selling for thousands of dollars are a mix of two dogs (which is really just a mutt).