From all my volunteer experience at the Vancouver City pound, and at the Burnaby and Vancouver SPCA, it was the pit bulls who were always looking for homes, and always the less than 'favourable people' looking to adopt the pit bulls. Sometimes, it would happen, a responsible person would adopt a pit, but not often, and it was often the pits came into the shelters. It is absolutely heart wrenching watching these poor dogs in shelters and how many of them and their cross breeds are there. And how many people declare, 'I would NEVER own a pit bull.' Well..it is no wonder that people feel that way.
Perhaps one day the SPCA will 'get on board' and start to really advocate for breeding bylaws so that only the dogs being bred are dogs that fit well within society...with people, with other animals etc. How much easier and more sane it would be if all the dogs who do end up at shelters are dogs with sound genetic traits that are safe to put into homes where there might be children.