I know with hounds, the better bloodlines have way better noses and other attributes that you desire in hunting dogs of any particular breed. Honestly, one can buy pups from some of the best Nationally known lines for a few hundred bucks. Figure the amount of time & pleasure that you will invest in that dog, why would anybody fool around with untested or proven bloodlines? Once you have hunted with good dogs of high class bloodlines, the difference is quite noticeable, no joke. One down side is often the better bloodlines seem higher strung or hyper in personality. Here in Alaska, people believe in certain bloodlines with sled dogs. I once had several dogs that came from a line that everybody wanted to breed into their teams. The Sheerer line was developed in 1990's the newcomer to dog racing ended up finishing in top 10-15 his first race. People sat up and took notice. I ran dogs from that line for 10 years and the quality stood out, my best dogs. Point is people have been breeding dogs for hundreds of generations, seeking to improve the traits they desire.
I had friends who had Chessapeak bay retrievers, everybody wanted this certain line and I saw those dogs hunt.
If you are looking for a pet, then the dog pound is a consideration.