Labradors are a very popular breed. With popularity comes mass production. Mass production brings on issues. There are breeders out there that pride themselves with lines that are without genetic problems. Some don't. Those who don't, strive for that "perfect" pup without any thought in it. Instant gratification. And will sell pups to others without thought at all as they are so focused on getting a perfect pup right away. Unfortunately these pups find their way into other breeding programs and if you don't do your research, you might find one of those "instant gratification perfect pups" in your line and it will wreak havoc. Also don't forget those designer labs that are out there too. Dogs that might have not been fit to be crossed into the Lab to make a designer dog, and then issues happen there. Not all pups from these designing breeding look like a designer, actually look like a Lab. Which find there way into a breeder's line.
Seen this in Rabbits. To find a breeder, you have to find out how they look at their line, how they look at breeding. Do they look at their line as a pet line, or a show line. If it's a show line, how long have they been showing? And how "into showing" are they? And for how long.
Breeder is just important as the line she/he has.
KAZ