When I was at Apple, we had a consultant who insisted on coming into work dressed like a professional consultant. The rest of us were in T-shirts, shorts and jeans, sandals or tennis shoes or hiking boots, a typical hacker crowd.
She wasn't getting much traction. It was awkward to have a "suit" in meetings, even though we knew she was an excellent engineer. A couple of us suggested that it might help for her to dress down. Finally our director (a woman, if it matters) took her aside and had a chat. A few days later the consultant started coming into work in jeans / t-shirt and so forth, and her interactions with us went a lot better.
The hacker in me wants to feel vindicated. But really it just shows how shallow we can be.
In any event, I am never, ever going to wear a tie or a suit to work.