I think in 93's scenario, I would've been more bothered if the guy was seated behind me, & had his bare feet propped up on the backing of the empty seat beside me. It's bad enough with shoes on, but are feet just makes it feel more.. filthy. Just from the contact it might have that other parts of the body may not.
Foot fetishes are odd.. some guy followed my friend when she was walking home, last year.. was driving slowly beside her a couple blocks, repeatedly asking her to show him her feet. Even offered to give her money. *shudder*
Another friend of mine sort of accidentally conditioned himself to get turned on by feet. He used to pretend he LOVED them, just to creep out his gfs, make them squirm away if he acted like he was going to put a toe in his mouth. Sometimes he'd manage to do it, I guess. One girl got insanely turned on by getting her toes sucked- it was a huge surprise to both of them. I dunno, after that he thought it was the coolest thing ever. ENTPs. *shakes head*