Not too keen on the word useless. Especially, without knowing more details.

I don't believe dogs are born gunshy. Case in point would be a friend ( I use the word loosely) than purchased a 3 month old dog from a breeder than I had gotten several dog from. He hunted with me and liked the way my dogs worked.
He called me later in the season complaining that his dog was gun shy. How did you introduce him to the gun I asked. He replied that he and three friends put some birds out and after the dog pointed they all cut loose over the dogs head. First exposure not good !

I know some dogs would never flinch at that experience, but that is not the way to find out.

The only way I would take a free dog is see him work in a realist setting.

Sorry if I sound hard, but the only reason I hunt are my dogs. Yes, they are GSP's , but they could be Pointers or Setters doesn't matter to me. I love all dogs that have a purpose.