Wow, this one is hard to answer. First I will like to see where the pups were raise and it what environment ,and see the pups parents if available.
Buying a pup from a car's truck screams to me puppymill or someone that donot care for the pups. In the other hand is scary having strange people coming to your home. I think that breeders and possible buyers need to be screen. I guess is a risk Like LvMyYorki said.