Originally Posted by
af101
Interesting several folks have all said it's happened to them. I'm generally rather scruffy when travelling (ok, not just when travelling), and nobody's ever tried to stop me going into Fast Track. I think a lot of it is just down to striding with confidence

I was going to post something similar. Generally if you seem confident in where you are going, people assume you are in the right place.
Yesterday on a US flight from PHX-BOS they boarded a few minutes late so I was casually standing near the priority area after exiting the lounge too soon. A few people rushed ahead of me to get their place in the queue. When it was time to board, they all started talking about how they didn't get upgraded. I said, oh, I'm in first and started to walk by them. They asked how I got an upgrade, and I casually mentioned that I bought a ticket in F. They were dressed in suits, and I was wearing shorts (it's hot in PHX still).
Anyway, the point is, many people make assumptions based on your appearance, body language, age and gender, and I wouldn't take it personally.