I've seen more than one devoted novice rescuer rehab a dog with the help of an experienced coach. Fortunately we have several such wonderful people at our local kennel club. It takes patience but I wouldn't just assume the worst.
The BC I currently run in agility was four months old when I took him. The breeder had four, four month old males, and was desperately looking for homes. Most went to farms. He was scared of everything. Not interested in toys, low prey drive. As a trainer I was stumped. He's now nine, an agility champion, has more titles than I had ever dreamed of having on a dog, and because of his gentle temperament has many fans. Patience, perseverance and love will get you there.