we used to try and get off-leash dogs to come on runs with us too. It got pretty comical some times.
I love dogs, but I did have to kick one. I was running by a house and the owner was trying to get in the front door, the dog was going nuts and pushed past the owner and ran straight at me. Having been in this situation before, I stopped and let the dog approach me as I had done a million times before on roads, trails, parks. When it comes to dogs, be the leader of the pack, be the alpha. Put a hand out and let the dog sniff it and know you are in control. Confidence.
This time though the dog didn't slow down, and the owner, very audibly said "Oh no". Which to me means this dog has been a bit of a problem and had a history of biting. So...I backed up into the street, let the dog come off the owners property, and kicked it square in the nose. It yelped, laid down and started pawing at its snout. Owner came over, angry at first, but when he realized I was cool and had done everyone there a favor he said "thanks, it won't happen again"