Puppy-peddlers include everyone from breeders themselves to rescue groups that are really making a profit from selling popular puppies. Some peddlers buy a litter of puppies from a puppy miller and sell them online in the classifieds. They may say their sister or brother breeds dogs locally when they likely come from a distant state.
Have you ever heard of a dog flipper? They acquire dogs and puppies from various sources and re-sell them like used-cars. Often times they will place dog wanted ads online.