What care do they give the puppies at puppy mills?
This depends on the breeder. Some puppies are relatively well cared for in the sense that they are kept clean and have basic vet care (for shots, tail docking, etc.). In general, though, puppies get just enough care to keep them alive so that they can be sold. Some breeders cut off tails and dew claws themselves with kitchen or garden shears to save on vet costs. Many puppies may never have seen a vet, may not have had enough to eat, probably lived in filthy cages, and may never have known a friendly human hand just petting them.