I was in a position at a roadshow where the only way I could make it was with a golf shirt, shoes and khakis - not an issue (though Capt America did give me a dirty look as i entered at five mins past start time as he was locking door - not sure because of puntuality or fashion sense!...; > )
At the end when I approached HR mgr with resume & apologised for appearnace and gave mitigating circumstances.
Called for interview shortly thereafter
good luck
f