You don't think dogs have their own signals? If you go over to a dog and it moves away what is it saying? It does not want you near it. So if you proceed to it anyways and pet it and it growls, now what is it saying? I told you I do not want you in my space, back off. If you then decide to hug the growling dog it is then telling you that maybe you should of listened to what it was saying.
Dogs will correct and teach other dogs, and they will with people too. If a person ignores the language and barrels ahead anyways then it is not good for the dog or the person.
Well of course this happens, that does not mean its right. A healthy, well adjusted dog will not do this to humans ever, unless like I said it earlier it is being truely mistreated. Owners who let their dogs get away with this behavior towards people are asking for trouble and are irresponsible, or are in denial about the monster they have created.
Dogs love to be treated as dogs. They need a leader to feel secure, like in a pack. That leader needs to be you! If not this leads to all kinds of behavioral problems and anxiety. The love to follow and have a job to do.
Here are some tips on maintaining your status with your dogs:
Always feed your dog AFTER you eat first.
Test dog by taking food or toys away from it.
Never let your dog on your bed
Walk the dog in a healed state most of the time.
Do not let your dog get on top of you
Remain calm and in control while correcting your dog.
maintain a confident posture while working with or being around your dog
do not leave the food bowl down for more than a short while.
Do not let your dog get pushy with you or let it lay where ever it wants
socialize your dog regulary with other dogs, not just the ones you have.
be consistant in your actions
When you come home to the dog walk right past it with minimal acknowledgement from you, maybe a hi, take care of your immediate bussiness then when the dog is calm give it some attention.
Just a few there are more, but this is what a dog needs to be happy, otherwise they become confussed about their place and the problems start. This is true love like Hedge said. You have to be the boss and a good parent and sometimes it might seem to some that it is mean, but it is not. The opposite is
I will say this again, The dogs do not make the rules or do what ever they want. At least in my world they dont.