I'm a 2nd year at NSU-COM...
Yes, you have to wear either:
Shirt and tie for men
Nice dress clothes for women (slacks, skirt, blouse, dress, blah blah)
or
scrubs
You are supposed to also wear your white coats at all times, too... but that doesn't always happen.
Wearing scrubs is great, by the way, its like going to work in your pajamas. You just roll outa bed and slap 'em on. Can't beat it.
And as for looking "unprofessional" in scrubs, and that bums wear better attire... I can say that when you walk around the campus (the other programs wear scrubs as well) and someone is NOT in uniform, i.e. jeans and a t-shirt, that looks unprofessional. When I walk around a hospital, I see everyone in scrubs, docs, nurses, techs, therapists... and that's fine with me. I don't smirk because they're not wearing a tie.