I wear the exact same boring ass skate uniform I wear everyday.
Skate shoes, jeans, t-shirt and hoodie.
I hate sitting next to most businessmen/woman who are all dressed up. About 50% of the time they try to talk down to me or feel they have the right to invade my space.
I remember bullshiting with the ticket agent and the dude upgraded me to first on a short flight from Toronto to NYC. The businessman I sat next next to wanted to store his bag under the seat in front of me so he could spread out.
Also, I've noticed I can always tell where I'm going based on people are dressed. Flying into Phoenix is always interesting. All the women have blonde hair, horrible clothes, and conspicuous jewelry.
And, the way people act on the plane seems to differ as well. I've noticed on the flights I've been on recently the Americans just entertain themselves and people in scandinavia are always working on some spreadsheet or presentation.