This British Journal of Psychology report will send you to the nearest animal shelter to find a pooch.
The psychology department at the University of Warwick in England tested the theory that people would be more outgoing toward those who had dogs. As expected, people indeed were more willing to approach a stranger if the stranger was walking a dog.
Then they tried part two of the study: One man -- dressed neatly, then dressed in a really scruffy outfit -- with and without a dog. Without a dog, nobody said hello when he wore the grungy clothing, and very few approached him when he was neatly dressed.
But when he had the dog, strangers approached him, even when he wore the sloppiest clothing. More strangers said hello when he was smartly dressed and had the dog -- but it was clear that the dog meant more than the clothing.