@RickiTarr I love telling the story of our rescue dog.
She was a puppy mill mom in an over-populated farm, and when the owners got wind that animal control was watching them they dumped the dogs out into the back 40 with the "we don't know whose dogs those are" defense, and shot any dogs that tried coming back to the home.
She had just had a litter of puppies; only she and one puppy had survived when animal control did claim them.
My wife adopted her despite the warning she doesn't like children or men -- my reaction was "you got a dog that's gonna hate me?" but she's my best buddy now.
When she arrived at our home she didn't know how to ask to go outside to go potty, but once she figured it out she has been perfect. She, surprising both us and herself, realized she knew the command "sit" and we found that she must've been trained as a puppy but those memories were buried under trauma. We hope those memories are long gone now, replaced by a good ones of her new home.