The guy that gave me the tour on our interview was dressed in well worn corduroy pants, an old T-shirt, and converse sneakers. The dean of the school was also there on interview day. While the dean was within hearing distance, he said that that a dress code was put out there as an idea last year and was rejected by the students. He said that he would "hate to have a dress code".
However, to help out my fellow SDN'ers, and in the spirit of evidence based science that we hope to one day practice, I've gone ahead and downloaded the general catalogue. I did find a dress code buried in there on page 23. Here is what it says:
"DRESS CODE/IDENTIFICATION
Students are required to dress in a professional manner at all times. During classroom lectures, students are required to wear clothing that is in good repair (no patches). Footwear is required at all times. Dress for skills labs should not be worn outside the laboratory area. Tank tops, halters, scrubsuits and headgear (hats/helmets) are not to be worn in the classrooms. Shorts may be worn, but no more than 3 inches above the knee. Hair, beards, and mustaches must be clean, net, trimmed at all times. Students are expected to conform to the commonly acceptable social standards of personal hygiene."
In other words: you have to wear shoes and shirts, no "dixie duke" shorts, and you must shower/shave enough not to be a stinky hobo.
No hats during lecture, but it's OK inside the building or on campus.
I wouldn't call this a "dress code" and put it into the same league as those schools that make you wear ties or scrubs. It's more like a code of hygiene. The students I saw walking around on campus were no different looking than those at UC Davis or UCLA.