Not necessarily I used to do rescue and they were put in the shelter because they were moving and could not find a place that took dogs. Most of the rescues I did were from owners that would not take the time to train and complained that the dogs were to unruly. I took them and found most are human error rather than anything. The yellow lab I took the owners said that she was so bad she destroyed the house when she was let in. But what I found out later they used to lock her up 8 hours a day then let her in the house. What dog would not go crazy after being kept from the family in lock down. I exercised her properly and she would walk in the house and lay at my feet perfectly happy. I think a lot of dogs are in the shelters because the people don't want to put in the time. I have always rescued from the shelter and have always had great dogs. If its a decent shelter they know their dogs.I wonder about those that are owner surrender with no reason. A warning sign?