If you want to adopt a rescue, I'd suggest you contact a rescue group rather than adopting one directly from the shelter. As megansmomma said, the way they act at the shelter is probably nothing like their real personality. They are traumatized by being taken from their homes, then put into the very stressful shelter situation.   
When private rescues pull dogs from shelters they go into foster homes. Then their personalities can be evaluated so they can be matched with the best possible adopter. The foster moms work on potty training and other behaviors.   
Not sure why you are concerned whether the puppies came from a pet store or breeders. Breeders produce the puppies to supply the pet store. Whether they came from a backyard breeder or USDA kennel, it really doesn't make much difference. Some backyard breeders are worse than the commercial kennels that are regulated by the USDA.        |