We all know this, but it’s worth repeating. If you want the chance to be upgraded to Business Class or First Class, dress the part. George Hobica, Airfarewatchdog.com:
But everything else being equal (same frequent flier status, etc.), when a flight is oversold in economy and the airline needs to upgrade someone, are they going to choose the passenger in the tank top or the one wearing the nice dress or suit? You already know the answer, (but as always, it doesn’t hurt to be extra nice to any staff you should encounter).
It’s a small sartorial sacrifice to make more room for the laptop or iPad.
Source: Ben Brooks Review