I'm not completely sure to what extent my expressions don't fit with my moods. A lot of times, people take me the wrong way, but I'm sure there are other factors to that besides facial expression.
My mother, however, has HUGE problems with the facial expressions thing. Well, it's not necessarily her who has the problem with it, but her who has the expressions that cause problems. Somebody may tell her she looks upset or disgusted, and she just kinda brushes it off, and says "no, no, I'm not upset.."
When your mother always looks upset and disgusted, though, that takes a toll on a kid. There have been a lot of people (teachers, professionals, etc..) who have seriously disliked me. The why on that frequently bewildered me.. looking back, I think at least part of it was that they assumed that if my mother seemed so disgusted while discussing me, there must be a reason for her disgust.