Dog training collars always looked so mean to me especially the choker collars. I had one for my dog when I was little. My dad used it to train my dog. Apparently, as the breeder and trainer said, they were the only really efficient way to train your dog.
However my dad was nice with ours. A little slight yank to get the point across and my dog was sure to respond. However, I have seen people be positively vicious with them; to the point that the dog cried out in pain. This of course is not surprising when the dog is lifted off of their feet by a chain that is choking the air out of them.
To me the whole dog training collar thing seems to kind of go against a lot of the other stuff I have read. Everyone seems to say that you should not yell at your dog when they do something wrong, but instead show them the correct behavior and praise them for it. To this end the choker collar seems to be a little out of the scope of things. Im not positive but I am pretty sure that choking your dog, whether lightly or almost to the point of death can not be considered positive reinforcement.
There must be other dog training collars that work just as well...