I've recently met a very nice lady in my village who has a dog. I suggested we walked our dogs together but she told me that she had a bad experience when her dog was a puppy where it barked and growled unprovoked very badly at another dog, so upset was she that three years down the road she walks alone in places where she's unlikely to meet other dogs. She's recently been to a dog behaviourist but was still lacking in confidence to walk where there were other dogs.
My two dogs are of similar size and very well socialised and very non aggressive so I suggested that we walked together, initially I would bring just one so as not too overwhelm her dog.
We met up on neutral territory, my dog wagged his tail and looked friendly her dog showed her teeth when mine got too close, mine backed off a bit, we went for a walk let them off the leads and apart from a the odd episode of teeth bearing when again mine got too close it went very well. My new found friend was delighted. My dogs are confident and outgoing (as am I) and her dog seems to be growing in confidence meeting a quite a few other dogs on our walks and simply ignoring them as does my friend. We've since done it three of four more times now my friends dog only shows her teeth maybe once sometimes not at all. I've now introduced my other dog to our walks, mine was friendly, teeth baring initially from my friends dog, mine backed off and then they all were off leads together doing their own doggy thing. Pleased my friend rang her behaviourist to tell her all about it, she didn't seem so pleased, she said the dog was unhappy and shouldn't ever show it's teeth to mine ever as she was learning that this behaviour works.
I'm no behaviourist but surely my friends dog was saying to mine "don't get too close mate as I'm a little afraid of you and don't know you yet" mine being well adjusted go "ok getting the message" and back off. Now they are happy too be very close to each other, even in a confined space; whilst manovering a kissing gate no teeth baring at all or walking down a very narrow path.