I’ve adopted from both shelters and rescues. There are a couple of differences:
1. Rescues are not gov’t funded, shelters usually are, which is why there is such a huge adoption fee difference.
2. Rescues sometimes specialize in one particular breed, shelters usually have a mix (but you can find lots of purebreds in them).
3. Rescues tend to have more time to devote to the animal, either by the workers themselves, or by foster families, that help to learn the dog’s behavior and work out any potential problems. They also learn the dog’s personality and can better match up a person or family with an appropriate dog. Shelters are usually spread too thin amongst all the different animals they deal with on a daily basis to give undivided attention to any of them.
4. Rescues are usually no-kill. Many shelters are no-kill as well, but there are more that do put down after a while.
I don’t want you to think I’m steering you towards a rescue since there are many good and bad rescues AND shelters. Do your homework on whomever it is you decide to adopt from. Ask around, ask for references. I do implore that you look for a no-kill shelter, though. Then you’re saving 2 lives….the dog you adopt, and the next dog who can come in and take that space. 🙂

You may find more dogs who have had problems in rescues but to say they have problem dogs is inaccurate. The problems have either been dealt with or they will let you know up front what the problem(s) is/are and exactly where the level of progress is. They will also be there (or at least the good ones will be) for you if problems arise for however long you want. A good rescue will be upfront and be available to support the adoption for as long as you want because they don’t want you or the dog to fail. In most cases these animals have been through enough and the rescue doesn’t want to see any more negatives happen.
Rescues usually use foster homes and can tell you the dog’s personality, issues and whether or not it will be a good fit for your family. I have a dog that came to me as a foster who had 5 potential adoptions fall through and there is absolutely nothing wrong with the dog. In one case the potential adopter lived in a very warm climate and wanted the dog to be an outdoor dog. This breed is bred to be a house dog and is very intollerent of extreme temperatures so the rescue said no. Another potential adopter for this same dog did not have a fenced yard (this particular dog LOVES to run!!), had some fairly unreasonable expectations for the breed type and most of the family was totally indifferent to the idea of having a dog so the rescue encouraged them to look at a different dog. I ended up adopting him myself and I can’t tell you how much he adds to my life!