My feelings about dog breeders, heh. I could fill a book.
So I'll try to give the abridged version, including my background.
Since the age of 14, I have volunteered and worked at various types of animal shelters, including high volume municipal shelters, poor rural shelters and well-funded private limited access ("no kill") shelters. I've cleaned kennels, learned my vet tech skills (that eventually helped land me a job at a clinic) by assisting the shelter clinic vets, been an adoption counselor and worked to help train shelter dogs. I've assisted with purebred rescue for Siberian Huskies and fostered difficult puppies and dogs.
I also spent one summer working as a kennel technician at a Petland, a pet store chain in the United States that sells puppies from USDA licensed commercial breeders and brokers.
As for my interest in vet med, it's companion animal genetics. So that, along with my background and experiences, explains very well why I have strong opinions on this issue. So with all that stuff out of the way, I'll try to explain how I feel.
Initially, I had the same attitudes as a lot of those that I hear from shelter folks - it's what I was exposed to, and so I didn't really think much about it other than "breeding = bad, adopt a shelter dog instead!" I held these opinions for a really long time, until I ended up with a husky puppy that I ended up rescuing from the pet store where I worked, that was going to put him down for a severe case of hookworms.
This was a short-term rescue and I knew it, since I was in no financial or stable state to take on a long term commitment like this, so I began to look for ways to rehome the pup.
It seems counterintuitive that my taking over a horribly bred puppy and looking into rescue would be the turning point in my attitude in this way. Basically, I started to do more research into purebred rescue, and got into contact with a lot of people who were involved with the local Siberian Husky rescue. To my surprise at the time, a lot of them showed and bred dogs as well. This was where I started to realize that there are responsible people who breed purebred dogs for a good reason. So what do I feel is the definition of a responsible breeder?
The first important thing, to me, is to have a purpose to breed. Whether a breeder is interested in conformation, agility, coursing, schutzhund or some other "dog sport," or they breed for service dog organizations, or K-9/military dog purposes, the breeder needs to have some sort of ideal that they are working towards in their mind. Dogs to be bred should be selected to further the breeders goals and work towards improving the breed in question through addition of sound, functional dogs from their line.
To have a goal like this, the breeder needs to be very knowledgeable about the breed they're involved with. Knowing the breed's history and original purpose, possible issues that may arise (both health-wise and temperament-wise), what sort of owner/household situation best suits the breed, some of the popular lines of the breed, and so on are all very integral to being knowledgeable and well-informed. Because of this, most reputable breeders specialize in one breed, sometimes two or three if they are related breeds or have a lot of expendable time and money. A lot of both of these things go into responsible breeding of purebred dogs and these people very rarely profit or break even. It's a hobby to most of these people, like other money sink hobbies that rarely pay for themselves.
A lot of people I know tend to ask me about different breeders when they're thinking about getting a dog, and a lot of times ask me to scout out ones they've found. I usually look at the breeder with the question of whether I myself would get a dog from them were I looking to buy a purebred of that breed.
The most important thing I usually look for initially is whether the breeders lines are healthy. This doesn't mean that they have yearly exams and vaccines and the vet says they're normal, to me. This means that the dogs have been tested for any appropriate genetic problems common to the breed - OFA hip/elbow or Pennhip testing, CERF certification, thyroid checks, any available DNA tests, and the breeder knows the health status of the dog's ancestors, as well. OFA and CERF have searchable databases, and breeders who do these screens are usually more than happy to tell you about it. If a breeder simply says that their dogs "never had any problems" and doesn't provide testing info, that's a major red flag. Once I'm satisfied that the requisite health checks have been performed, I look at what the breeder does with the animals.
Conformation competition (showing dogs) is great, but I don't see it as the be-all-end-all that some others seem to. I've seen some breeders with the attitude that slapping a Ch. title on a dog means the dog is okay to breed. I feel like function is more important than form, and if a dog can do what it's meant to do, then that's more valuable to me than whether the angulation of the animal's ears is precisely right or not, or whether the dog lines up with the current trends in the ring that the judges are looking for. Dogs with conformation errors who perform well for their breed's original purpose shouldn't necessarily be excluded from breeding just because they can't get titled, and I'd take an Afghan with a less showy coat who can chase down bunnies over one with perfect coat who can't course any day. I don't feel like there's some all-inclusive "do this and dog is ok for breeding" threshold, there's just a general feeling that's hard for me to quantify.
Generally, the more open and honest a breeder is about their breed and lines, the better. More details is never a bad thing. It's also a plus if the breeder is involved in rescue, and requires pet puppies bought from their lines to be spayed or neutered or only offers limited AKC registration for pet puppies. It's also good if the breeder remains a lifelong source of information and will take back dogs or assist with rehoming if the puppy doesn't work out for any reason.
Obviously pet stores and most people who advertise in the newspaper, and anyone breeding designer dogs, don't fall under my classification of a responsible breeder. I also still do think that a lot of people who want a purebred dog would be just as well served adopting a dog from a shelter instead. But if people have specific wants and are going to get a purebred, I just try to educate them and hope that they make a good decision about where to get the dog.
So, not quite a book, but maybe a novella here...hopefully I clarified my points well enough. I suck at writing essays.