We adopted a dog (and then I volunteered with this group). Their standards are excellent! They make sure the dog is a good fit and placed in a safe and loving home. Every effort is made to ensure their dogs find a "forever" family or home. If, by chance, problems arise with the dog, they quickly respond and make every effort to find a cause and solution.
Bichon Furkids has done a phenomenal job in rescuing hundreds, if not over a thousand already. Their plan is simple, place "unadoptable dogs" in homes with volunteers where their real personality comes out, evaluate them, and then match them with the right family.
One must consider that shelters are not a good place for dogs to be evaluated. You can have an otherwise gentle and sweet natured dog become "vicious" in a shelter when they smell death all around them. 99% of these dogs thrive in home situations and become gentle members of their adopted families.