In a very short form:
"SOUNDNESS, TEMPERAMENT, HEALTH", after this "BEAUTY"
Red cockers have a bad temperament - some people say.
We say: It is not true. We have up to 5 red cocker bitches. They live together without problems. We got a child, most of the dogs were rather old in this time. But they had no problem to accept a baby.
The breeder, his philosophy and the way puppies are reared is very important in the development of a dog. Under "perfect" conditions socialized dogs are not aggressiv, independant of the breed.
With the few litters we had, we must have an other job to earn money :o) Some dogs must produce litters to pay the bills of their breeder. We are working to pay the bills for our dogs ;o)