I think a lot of people misread facial expressions and body language in general. I'll often feel neutral or be day dreaming and be asked what's wrong. And my nervousness is often viewed as attitude or "ditzy".

Since I've been treated like crap in the past, I view almost every interaction as someone's attempt to be mean or scheming. Because of that I can come off as being standoffish or even confusing to a person because I would love to be thier friend or get to know them but I don't trust thier intent.