What originally put me off adoption was my MIL's horses, her rescued STB's. She cannot take any definitive action with her horses, without the approval of the rescue, and that includes vet care and putting the horse down if the situation calls for it. So if her horses had a major accident and were suffering, and putting them down was the only option outside of expensive surgery, she would have to contact the rescue and gain their permission in order to go through with it.
We recently adopted a beautiful purebred dog from a local pound, not humane society based, but city animal services. In the short time that we have had him, we have come to the conclusion that he has been heavily abused (read beaten) by who ever had him before he was recovered. We were looking for a specific breed (German Shepherd Dog), and like our last one, we wanted to go through a rescue or the pound or humane society to find one. Not a problem, it takes time, but they are out there. Man, when I started researching the local GSD rescues.. We did not go through a rescue because we do not have a fenced yard, it was an automatic rejection of adoption request. We provide an excellent home, food, water, comfort, and affection is abound. We meet any and all other wants/needs/requirements. But we don't have a fenced yard. We walk 4 times a day minimum (before work, on lunch, right after work, and before bed), sometimes more just to get out if the weather is nice. If my new pup wasn't so traumatized, we'd be going on hikes too, but he can barely walk out of the yard right now before laying down and turning into a fit of trembling fur. I would have happily gone through a rescue for a sane, loving, well adjusted dog that I would never give up. But they won't adopt out to us. We found our dog though, and we are working on adjusting him to a "normal" life of love and rubs and kisses. **** if I didn't wish he'd be ready to jump in my lap for some snuggles right now though instead of huddling up in a corner.
Rescues just are not practical. Won't adopt to certain lack of wants. Won't adopt outside of certain mile radius. Won't adopt to people with lack of veterinary repertoire. It's ridiculous. Have to have certain diets and follow certain rules for non special needs animals. You are even less unsure of what you are getting out of the humane society, city/county services, craigslist, or auction, but at least you own it and have control of it when you go that route.