There are often Parvo outbreaks in the feral ends of town - you know the area where most of the dogs were bred in someone's back yard, most dogs are not desexed, nobody gets them vaccinated and they're not real big on taking the dog to the vet when it needs.
And then it's traumatic for those whose dogs are there. We have a few dog clubs in those areas and I would not want to take puppies there and would probably want to wash shoes in disinfectant on return.
Vets often have an idea of where the outbreaks are too. Not that you can't get a new one - but you'd have an idea of where to avoid if you ask the vet.
Play dates in the yards of vaccinated dogs - are probably less risky. But it can be tracked in from outside on people's feet and dogs paws.
So really tricky choice = a dog that doesn't play nice with other dogs or risk a puppy that gets sick and dies. I guess I see a lot more dogs that don't get along with other dogs than I hear or read stories about puppies that get sick and die and most of those - the problem was traced back to the breeders ie the puppies were sick before they got taken home.