I got my girl, Jade, from a breeder who, after 3 litters at nearly six years old, just wanted to find the right home for her. She did not charge me for her, just mandated that I get her spayed and take care of her. I send her updates and photos now and then. Jade has some issues, which is why her owner wanted a very experienced home for her, but things have worked out well. I don't think I would pay for a dog a breeder is re-homing, however. Tells me that the dog's best interests aren't necessarily the breeder's priority. The flip side, though--having to pay for a dog can ensure that the dog will at least have some value in the new owner's eyes. But Jade's owner knew me already and we had a couple other connections, so she knew what kind of home Jade was coming to.
I have given away a dog to someone I didn't know, but I felt that he would actually be a great home for her, and it turns out, it was. However, just like giving away puppies, giving away adults has just as many negatives.
I mean, let's say you took your free 6 year old bitch and bred her 4-5 more times, and then dumped her in a shelter or shot her in her head. Your breeder should have spayed the bitch FIRST, and then placed her in your home for the cost of the spay.
Also, people have their girl friends and wives go meet breeders and tell them all about how they want a dog who will be a companion to them, blah, blah, blah, and then they hand the dogs over to the boyfriend, all for free, and the boy friend uses them for bait dogs.
A person who cannot afford the dog, will also not be able to afford the surgery that the dog needs when it tears and ACL or bloats. They call the breeder and expect the breeder to foot that bill too.
Sorry, but a dog is worth paying for. Even an older dog. Maybe not the same as a puppy, it depends on the dog. A puppy you cannot have information of hips and elbows, etc. A puppy will not have a significant amount of training in them. A puppy can be a crap shoot with temperament.
And there is this: sometimes people value more what the shell out for. Sorry, but the dog you got for free because his testicle didn't drop or his ear didn't stand, well that dog is defective. Some people won't even bother to contact the breeder when they decide to move and, awe shucks, just no place will take a dog, better drop it at the shelter. Hopefully breeders can judge people and recognize the breed, but sometimes life happens, the dog ownership changes hands, and even that, if the dog is worth anything, well, they rehome it for nothing, and well they dump it for nothing.
Don't tell me people pick up dogs at shelters and never dump them, because the facts are otherwise. People rescue dogs from shelters, and then dump them when it is inconvenient.
Hopefully the retired breeding bitch, who probably has more than half of her life left is well-bred and good tempered, with passing hips and elbows. That may not be worth anything to some people. It is worth plenty to others.