I should also clarify... I am against abusing animals. I just view training(as long as it's stuff like what WarKitty described, where the training causes no harm*) as a perfectly fine acceptable thing to do. Especially because it is possible to tell if an animal is unhappy.

*though harm in the form of something like "brief mild harmless zap from an electrically charged fence used to keep large animals(cattle, elephants) in/out of an area" is more okay since it's very brief mild thing that's much safer than the alternatives.