I witnessed male worker fired on the spot for wearing jeans to work instead of slacks (general motors). I was also once given a warning when my belt and shoes did not match (black and brown).

I went to a business college, and we were taught to dress professionally, I think we spent a full day on the topic in "business communications" course. We most definitely discussed that cleavage should not be shown and dress length should be appropriate. I worked in this college as a tutor, and we also required button-up shirts, tucked in, with a belt, and dress shoes, even though we made minimum wage. "Dress for respect"