Ask to see pedigrees, certifications, guarantees, contracts, instructions, medical records and so on. Expect to be interviewed as though you were adopting a child. Reputable breeders puppies are not raised as a cash crop, but to benefit the breed through careful, judicious decisions on health and quality. Pet store guarantees often are for only two to thirty days. If pedigrees are available, the sales force knows nothing about the dogs listed.
Most mass producers have filthy, depressing conditions in which their dogs are raised.
Many have crates piled on top of one another, with the excretions of the dogs in the upper crate falling on those below. Dogs don't run and play in the sunshine. They live their entire lives in confinement. Dogs aren't handled daily. Food may be thrown on the floor along with the filth.