Stereotyping people because of what they ride (or any other reason) is really ignorant...
If you dress, talk, and walk like a hoodlum, you can expect I will treat you like a hoodlum until you prove I should treat you otherwise. This is just a fact of life, one most of us accept. I don't go to job interviews looking like a homeless bum.
I associate snowboarding with generally clueless punks (and older people making a sad attempt at remaining relevant) who don't get out on snow much. Most of the time I'm right. Sometimes a few snowboarders prove me wrong in a big way. What else is new. Such is life.