Even though i don't take public transport anymore, i find that i still do it out of habit even now. In class, at college if i see a really hot girl in class, i never sit next to her. Why? Not because i lack self confidence, but because i don't want her to think that i'm sitting next to her just so i can talk to her. I just figure that hot girls get hit on all the time, so they assume every guy that comes near them, is trying to talk to them.
It's funny too because it can work in ones favor, because this is how i met my wife. I met her on my old job. She's hot, and all the guys at my job were hitting on her for months when she first started. But i barely said two words to her because i figured guys are trying to talk to her all day. In fact, if i saw her walking my way, i'd look away and avoid eye contact. Now, that we're are married with kids, i asked her, "Why me?" "Why of all the guys on the job, did you take interest in me?" She told me it was because i was the only guy that
never hit on her.

And she wanted to see whether i was gay, or just didn't find her attractive.In the end, she said it was refreshing/attractive that someone wasn't hitting on her. This won't wok with all women, as some loved to be chased, but in my instance it worked.
I've heard this from other ppl i know too, who are hot. Hot ppl are so used to being hit on, that when someone doesn't hit on them, they start questioning themselves, no matter how good they look.