I know how they train K9's and it's not pretty. It's why the dogs are wired and hyper, and they don't live very long.
Being a police trainer and K9 Unit manager, it would be easy to take offense to such ignorance. I don't but would like to know exactly where you get your information. I have a 50 dog unit. The current average age of my "fleet" is 6. I just retired a bomb dog that was 13. At 11 he placed third in the nation in a national competition. He was actually tied for second. The tie breaker was the actual time it took the dog to complete the search. He was beaten by a 3 year old malanois by 12 seconds. I've had many dogs work into their 10th and 11th year.
Of course police trainers select dogs that are high drive, high energy. While there has been, on occasion, trainers that go overboard, regardless of what people think, they are rare and usually dealt with. Not to sound melodramatic, the dog is relied on and must be able to perform. What we do is not sport, it's not competition. We don't work with dogs as a hobby or just for the fun of it. While indeed, there is a special bond between a police officer and their dog, they still have the mind set to send the dog into a situation that could well cause serious injury or death. Yes, there may well be some aversive training when training police dogs. I think most would be surprised however, well over 90% of all police dog training is using nothing but positive reinforcement.
I've fought this battle my entire career of seeing police trainers maligned with the "yank and crank" philosophy. Generally those tales are told by the person that knew a person who once talked to the mechanic that was third cousin to a police canine officer. Then it's reinforced by some bonehead police trainer doing something profoundly stupid.
More to the thread. With few exceptions ie, some tactical moves, explosives used and search techniques, there is very little secretive about police canine training. I'm a state agency. People are permitted to attend, to view, our training. There isn't any double naught spy activities going on, unless it's double naught spy activities. That would be work though, not training. Dog training is not rocket science. There isn't any smoke and mirrors. The basic principles pretty much apply across the board. Response, reward = response. No different than teaching a dog to go through weave poles, retrieve a down bird, pursue and hold a suspect. It's all pretty much the same.