i used to believe all that stuff too. "If you let a dog play with another dog, they'll be more fun than you, and your dog won't listen."
"You have to train your dog to only focus on you, letting them play with other dogs is dangerous".
"what happens if you're out working and your dog sees another dog?" "it will want to run off and play and get distracted and not work"
I have since come to a totally different conclusion. I think it's something that people might believe, but isn't actually real. one of my dogs loves, and I do mean loves to play with other dogs, all dogs, big and small anytime any place. that said, a dog could be humping her, and has tried when we were doing work and she didn't even blink at the other dog.
I think any dog worth a darn can easily focus on the task at hand regardless if it plays with dogs or not.
So I think that yes...Police K9s or any service dog...needs to be well socialized, but not allowed to be over stimulated by outside sources....as a reward or relief.
Several of my grooming clients regularly go to "doggie daycare" at a local training/boarding center. There is a playgroup of some dozen-odd dogs that run, play in the water, play with toys and people and each other all day long.
After roughly a year and a half of working with these dogs, here is what I have noticed.
The dogs are, generally speaking, friendly and fairly confident, obviously well-socialized, and in good physical shape. However, it is easy to tell which dogs are actually *trained*, and which dogs are simply thrown into the playgroup to release energy, in lieu of any training, just to keep them exercised and easier to live with.
The dogs that are NOT trained are self-absorbed, spoiled BRATS. They are used to doing exactly what they please all day long, and become offended and sullen when a human attempts to tell them what to do. Not only that, but they are athletic and used to the dodge/evade/wrestle game, so they are particularly adept at trying to get away from me or thwart what I am trying to do (bathing, brushing, etc).
These untrained dogs tend to have a hard time standing still and do not relax. If they only come in occasionally for grooming, it takes a long time to get them to accept the idea of being groomed, of standing still, cooperating, or at least tolerating something they don't necessarily want. While not aggressive per se, they tend to be fiesty and mouthy. It can be quite frustrating to groom these beasts.
OTOH, if the dog is in a training program apart from the playgroup, or if the owner at least works with dog and he is accustomed to being groomed and handled a lot at home, they are wonderful to work with. I have an Old English Sheepdog that comes in at least every two weeks, and his owner does a lot of brushing at home. Old English are notorious for bad temperament and a willingness to bite, but this boy is great. Because he goes to the playgroup twice a week, he is in good physical shape and therefore can jump into the tub and onto the table, and stand for as long as I need him to. Since he has burned off energy, he is calm and able to relax, and since he is groomed so frequently, he has learned to cooperate and--dare I say--enjoy the process.
There are a couple other dogs who go to the playgroup, that have also been thoroughly trained by their owners, and I only wish every dog could be so well-behaved and calm in my grooming shop!
So the moral of the story is, socializing with other dogs in well-organized and supervised playgroups, while a positive thing for the dog, is NOT a substitute for training. It may make them easier to live with because they have burned off energy and had mental and social stimulation, therefore they aren't as bored and destructive in the home. But if the dog never has anything asked of him, if he's never learned any kind of obedience, self-control, or anything with *humans*, he's not going to be easy to work with. He'll likely be great with other dogs and that's about it.
Playgroups are a wonderful *addition* to training.