Like several folks in this thread, my dress is often based on the trip/situation. In the past at least, if I was headed to a client site the day before meetings, I'd be in nice shorts and a polo style shirt. Obviously if I had to hit the ground headed to a meeting, then I'd be wearing whatever the client site's dress code required.

Personally, I've only been questioned once (the 6'7" part might have something to do with that ) which was by a passenger, and I happened to be on a paid F ticket that time to boot. Guy in line behind me muttered something about only first class boarding and hating people who try to board when it's not their time. I ignored him the first two times, then as I got to the GA he asked the GA "Didn't you say ONLY first class was boarding?". The GA already had my boarding pass in hand and politely told him that I was traveling in first. I turned around and told him he might want to allow his brain to work a bit before opening the lips, smiled and boarded.