I certainly understand working/hunting/sled dogs have to be of a defined character to do what they do, so buying might be the right source, if they aren't from "puppy mills," commercial operations of dubious repute. With rescues, my method is to spend a long time looking and sitting with animals to get to know their character and behaviors. Not all cats, but many cats, just like me. I can sit down on the ground and let them come to me, and they pick up on my being well trained and apparently trustworthy, so with some animals, my socialization to them is speedy. They really size you up. The current brother Maine Coons latched right onto me. One of them fell asleep with my holding his paw between my fingers in the first half hour.