I think its a shame if all indescriminately bred cockers (or any other dog) are tarrred with the same brush - it must be really disheartening for a new owner of a pup who may have inadvertantly bought a pup from less than ideal cicumstances
I do not doubt that a small minority of puppies from litters that have been bred indescriminately may grow up to exhibit behavioural problems that can be attributed to their genetics in some way or another. I also agree that early socialisation is important and can impact on the way in which a dog views the world.
These are a tiny minority of the whole, though - and I think the issue should be kept in proportion
In every town, there will be far fewer dogs (of any breed) bred by what we refer to as 'reputable ' breeders - ones who only breed dames which are sound in health and temperment, who select the sire based on the genetics and temperment of the dame and who provide a comprehensive socialisation programme for their litters.
Despite their "less than ideal start" in life, the majority of these dogs are well balanced, well integrated into their families and never experience a controversial moment in their lives
I know that if you own a dog that develops behavioural problems, it seems really unfair that out of all the dogs without problems, your dog was not so lucky
I have experienced the huge raft of different emotions when your dog becomes unpredictable and/or aggressive, and the desire to find an explaination for it.
For a long time, I was very negative about rescue dogs, because that was the "reason" I attributed to Shebas aggression; but over time I have accepted that it was not the reason; and not all rescue dogs will become unpredictable. Similarly, I hope that people don't assume all puppy-farmed dogs to develop problems, because many don't. I am not suggesting people buy indescriminately bred dogs - but if someone has, temperment problems are not inevitable, althuogh I accept the risk of health or temperment problems is greater.