In a techie environment, during a more formal event, I saw a gray fleece pullover used to de-borgify a CEO-type outfit.
uhhh, perhaps a translation is useful:
In the world of high tech, where a sportcoat, odd trousers, and tie marks you as administrator with money control ("a suit"), it is nearly impossible to be in both the techie and administrator worlds simultaneously. Jeans and a sports shirt or fleece marks you as techie. Going partway with chinos with oxford button down just marks you as middle manager. The brilliant solution employed was gray flannel pants, crisp white point collar dress shirt, tie, and a gray fleece pullover. It looked like an administrator slumming it with the techies, but the grey fleece gave it instant credibility. To the other administrators he was going casual, but then, so were they, by using sportcoats.
In the end, the guy put on a jacket, but his jacket was the traditional wear of the techies instead of the landed gentry. Subtle, effective, stunning.