I would never be interested in breeding dogs. I've purchased two dogs from show breeders and also have a good friend that breeds champion vizlas. These people research and research to know as much as they can about their breeds and bloodlines. It is much more intense than I had ever imagined. Sometimes traits that don't appear in your dog can still be present in the bloodlines and when bred with another dog with particular traits can then show up down the line. They have DNA checked and they spend a lot of time to make sure that whatever breeding they do is for the good of the breed. I just don't have the time or energy to do that much work.
On the other side of the coin I have owned a cocker spaniel that was bred by some lovely people who adored their female and wanted to have babies. They found a champion male, bred the two and produced some really bad tempered babies - fear biters, nervous, etc. It would be my luck to end up with puppies like my Ebony, who we loved but put up with for 14 years till she died.