The success is based on canine and owner participation. The only owner I can't train is one who doesn't want to learn ? and that's unfortunate for the dog. A lot of the dogs are turned over to shelters because most people haven't come across a training technique that works.
A lot of people feel that if a dog has nipped, growled at or bitten someone there's no hope for that dog. Nearly 99 percent of the time a dog like that can be turned around if an owner is willing to work with it.