It may be helpful for you and your wife to mutually agree upon your definition of a "rescue."
Some examples:
-Dog bred from hunting lines, and trained to hunt, whose owner dies, becomes disabled, and can no longer hunt with the dog. Owner or owner's family might want the dog to go to a new home where it can hunt, rather than just be a house pet the entire rest of its life. When my uncle passed away he had a 2-year old yellow lab trained for waterfowl.
-A breeder of hunting dogs who has a dog with a defect, such as one eye, runt, 3 legs, etc., who can't sell the dog and might be willing to depart with them for no cost. I've had a one-eyed English setter puppy, and a deaf Gordon setter offered to me for free from breeders.
My current dog is a lab/vizsla mix, approx. 7 years old. I rescued her five years ago from the roadside in MO. She is an awesome family pet, very clean, great with cats and small children. However, she does not hunt. No pointing instinct, hates water, hates loud noises, overly hyper/excitable. I taught her to force fetch, but she has very little interest in birds. She likes deer, rodents, and rabbits, and can catch the latter two on her own with blazing speed, and she is kept on a short leash during fawning season. However, no inclination to hunt for a human. I never expected her to. It's a major dice roll to try and hunt with a dog with unknown heritage.