I've gotten two jobs and an internship following this advice. My first job out of BYU was in a manufacturing plant and the hiring manager specifically told me to dress business casual for the interview. I showed up in dockers, a polo shirt and nice shoes. The other guys showed up in suits. After interviewing, we toured the plant. The guys wearing suits were wishing that they had listened to the instructions at that point. I got the job offer, and they didn't.

I followed this same strategy when I was interviewing for my MBA internship. We were told to dress "business casual" for the on site interview, so I did. The other guys showed up in suits and I had a button down with slacks and nice shoes. I got the internship.

Don't get me wrong, I've also dressed very formally for interviews in the past, but I've learned along the way to do my homework. My current job is for the most laid back company that you could imagine, so when talking to the recruiter before doing my on-site interviews, I asked specifically how I should dress in regards to the company culture. He told me to dress one step better.