the proper way. no faith in a trainer using them. I use a harness or regular collar and try to not let my dog get a running start when I have a long leash on her (yes, I do yse the 32 foot ones sometimes. It is good when I am sitting int he park and she wants to wander. I just can't relax while she is doing that, must check for squirrels, etc. )
I took my dog to training school and she graduated most improved. but she just can not learn to not chase squirrels, no matter what, it is bred into her and so be it. That means, unlike my very trained late border collie, this dog is never off the leash anywhere except in the house. I think the collar tells more about the person using it than the dog.

not to mention as a torture device. I've always used a prong collar with my dogs the RIGHT way that makes that nasty crap impossible. The only way that could have happened to a dog is that the wrong size was used, put on wrong and the dog was hung by the leash.

A harness does not control a dog. Harnesses were invented specifically for the purpose of NOT controlling a dog in situations where the dog shouldn't be controlled such as when the dog is tracking for whatever purpose. The only way to have control of a dog on a leash is to control its head. With a harness all you're doing is pitting your own strength against that of the dog in order to try to control it, and with a dog of any size you're strength is no match. A harness gives a handler no way to give the dog direction.

Prong collars have been around for a very long time, are much safer than choke chains, but like anything else must be fit and used correctly.

They are a tool and need to be used correctly, but that is like all tools.

I don't use one since I don't have to with my 33 lb dog, and I used to think they were just awful myself until I saw other people, who I knew took proper care of their dogs, using them appropriately. A friend I take my morning walks with uses them (properly) so that her two Labrador Retrievers don't see a rabbit and pull her off her feet, same thing with another good friend of mine, who has two German Shepherds. Their dogs are fine and neither humans nor dogs get pulled in front of any passing cars because SQUIRREL.

We need bad dog owners to be banned, or at least educated, more than anything. A person can injure their dog with a flat collar if they are an idiot or just don't mind hurting their dog.

I had a German Shepherd years ago that I didn’t train properly and I was naive regarding how powerful he was. I had several other large dogs previously but none as powerful as Edison. Edison was great at home but by the time he was about a year he was lunging at other dogs when we walked and barking ferociously at passersby. He weighed about 90-100 lbs. and I could barely hold onto him. I knew I needed to do something.

I enrolled in a local obedience class at the park. The first class was horrible. There were about 20 of us; each with our dogs standing in a circle. My dog was the only one who would not stop barking and jumping and lunging. The instructor asked me stand apart from all of the other dogs and said she would "deal with us later." I was pretty sure she would tell me I needed more help than she could offer.

The first thing she did when she was able to deal with us was grip Edison's muzzle and hold it closed and say QUIET! and then quickly let go to stop his barking. When he started barking again, she repeated, etc. etc. etc. She then instructed me to get a pinching collar (like the one referred to in the OP) and bring it with me the following week. We practiced the QUIET! routine at home that week and returned with the unused pinch collar the following week. She helped me fit it properly and showed me how to quickly pull it tight and let go when he started to lunge.

This is the same action you are supposed to use with a "choke chain" collar. Edison did not respond to the choke collar but he immediately stopped jumping and lunging when the pinch collar was used.

By the 3rd week, he was completely transformed. He walked properly on the leash and did not bark. We were able to participate right next to all of the other dogs and switch over the choke chain collar. It was really miraculous.

Having said all of that, I would not use one today. I have learned how to train a dog from the very beginning not to have these behaviors.

The photos in the link show a dog who probably had the pinch collar on 100% of the time. That is a horrible misuse of the collar.