Lots of people (even good friends) have told me that they initially thought I was a 'biatch' or intimidating when they first met me, which is really odd considering that I'm extremely outgoing and nice to everyone until I have a reason not to be...which isn't that often. I also don't think I'm especially scary looking. When I ask them about it, they can never give me a straight answer as to why they thought that way, though.
In retrospect, I think maybe I do have funny ways of showing people I like them, and maybe I assume that people can read my mind.