I once fortuitously blew my own chances during an interview. I had asked the headhunter what the attire was at the company, and he said, "Business formal", so I showed up in a suit. Whoops! I was the only person in the office wearing a necktie, let alone a suit. Then it turned out I had over a decade's more experience than their most senior developers, and my in-depth answers and questions about their products seemed to unnerve them. I had a co-worker at a later job who had previously for that company, and he told me many reasons I was lucky to have escaped getting a job there. TJNTIY.