Characteristics of a Bluffer?

[Tron]

Are there any physical characteristics of a person that will earn them the repuation of a "bluffer?" Such as their posture, their conduct, or even their looks? I ask this because I was just at your typical college-dorm No-Limit tournament, playing tight-aggressive. I earned this reputation before I even saw a showdown. Who knows, it could have been my betting structure, but what type of person do you think would earn, "He seems like the kind of person to bluff," at your home game?