The thing is, these people are very craft, you don't get to see the filthy puppy farms. They often take the puppy into their house or a friend's house and convince buyers it's home bred, making an excuse for the absence of the mother (she's out for a walk, or at the vet with an infection, etc)
The ones investigated were being sold from a bungalow in a reputable area but the day before had been caged in a filthy barn about a mile away.
People aren't stupid. They wouldn't buy from a dirty, puppy farm. They are lured in by these websites. Some of the puppies pictured on them aren't even in this country,
My daughter, an intelligent teacher, nearly got lured in this way so it can happen to anyone.
Do not buy puppies off the internet