Being a dog lover I'm familiar with the issues when bringing home a new dog, especially adult ones, and worries about how they'll behave. I found this article that talks of postures and such among dogs. I think it could prove useful in judging the threat of other dogs when out, you us owners dont have to be as stressed by an approaching dog
Body Language in Dogs: how to read what your dog is saying, from Stacy's Wag'N'Train