What about if you upgraded on the phone at the 72 hour point for Elites or at time of booking for SE? AC doesn't have videophones yet.
I have been upgrade wearing shorts, golf shirt and sandals without socks. I had shaved and was wearing a hint of Paco Rabanne Pour Homme. In today's dress standards, denial of an upgrade based solely on dress (unless one were considered indecent to the average person) would be tatamount to a form of discrimination.