I have also noticed the "friendlier" phenomena when I am riding in my commuter/city type riding clothes on my Jamis. They are all actual cycling clothes, but look more like regular stuff, i.e., skorts, capris that are urban looking, and shirts that have wicking material or lycra/sweatshirts, etc. The friendliness also extends to other roadies, as I think that my Jamis Coda is unique looking enough that riders look at my bike to figure out what it is.
I always get smiles when I ride up to local stores.