Many dogs get a reputation for being dog aggressive, when they are 
simply responding to adolescent dogs with rude behavior. My foster beagle was one of those very rude adolescent greeters who invades other dogs space without an invitation. I knew he would eventually receive some feedback, I just wanted it to be an air snap or nip and not a level 3 grab and shake.
Well, it finally happened, as I approached a neighbor with a calm female labrador, my foster boy wanted to walk right up to the labradors face who was standing tall, motionless, mouth closed tight, tail a bit high and not looking at my pup at all.
I could easily see my boy was not being invited into the labs space, but hey, he has to learn to read his own species body language as a part of growing up, right? So, while I slowed his approach, and his body was wiggling, the labrador showed her teeth and snapped at my dogs face, again, my foster pup wagged harder and tried to approach a bit lower and more submissive, he was once again met with lots of teeth along with an air snap. Understood! The beagle finally understood the labradors signals that he was not invited into her personal space!
My pup calmly walked farther away, sat down and never again 
looked at the labrador as we continued to speak to one another. My neighbor apologized profusely and would not stop going on and on about how rude his dog was!
I let him know that it was my foster dog who was NOT invited into his dogs space! In fact, his dog was very clear when we were 20 feet away that she was not interested in visiting. Many puppy’s and adolescent dogs need a few reminders to respect the space of others.
If your dog invades another dogs space who is looking away, standing stiff, immediately sniffs the grass or scratches himself, then he is not inviting your dog near him. This dog may send more obvious distance cues in the form of a growl or snap. This is not aggression, it is simply normal distance cues from one dog to another, a request for one dog to move away.
In my experience, humans have unrealistic expectations of how our dogs should behave. How can we label dogs when most of us have very little knowledge of how dogs communicate. If you are a dog owner, please take time to learn more about dog behavior and body language cues before saying your dog is aggressive. It is very possible your dog is simply reacting to the other dogs rude behavior!