It's incredible how the preconceptions of folks works. I was recently wearing a suit and you'd be surprised how incredible everyone treats you, especially in stores. If you walk into a store with a suit, people assume you are respectable (ie have money) and they will serve you immediately. For all they know, I could be a murderer walking around in a suit and the staff at stores wouldn't know.
The best is going into a Wal-Mart in a suit, which I have once done. A suit is so far beyond anything anybody wears there that it just confuses the employees. At Wal-Mart, as long as you're wearing pants and some kind of stitched cloth around your torso, then you're good to go. Wearing a suit to Wal-Mart is like swatting a fly using an atomic bomb. It's super-over-kill.
I think this would be a great sociological experiment. Take a criminal, dress him in a suit and parade him through stores and see the respect he'll get. And then on the other hand, bring Gandhi in wearing his robes and see how people avoid him.