Thanks everyone for the feedback. I'm good with telling me that my own dogs need space (Zeek wears the In Training vest).
My questioned was prompted by our shelter dogs. We take them out to adoption events so people can meet them. Of course, we choose the dogs very carefully that we take (make sure that they can handle all the stimuli and will enjoy the experience), but you know a dog reacts differently to different people and situations and can change from minute to minute. We watch the dog's reaction's very carefully, remove them when needed, and give them regular down time throughout the event. We try to educate people on how to properly greet a dog, but you know - everyone is a dog trainer and knows all about dogs.
This weekend we had some dogs out at an event and a woman (supposedly a dog person) approached one of our dogs head on, came over top of her, and got right in her face. Not surprisingly, our girl was scared by her approach and told her so with a lunge and teeth bared. She didn't make contact - thank god! And I don't blame our girl for her reaction. It all happened so fast that the handlier couldn't step in front of her or re-direct her.
As the event coordinator, I take very seriously my responsibility to keep our animals safe, happy, and successful. (The consequences really are life and death for the dogs in a city shelter.) There has to be a way to communicate to people politely and effectively how to approach a dog, without scaring off or offending potential adopters, and BEFORE anyone is put in a potentially dangerous situation.
Sorry, if my original question wasn't clear. I was really worried for our dog and wasn't being all that coherent.