When I stopped eating fast food regularly, I started being able to pick up the "off" odors in things. I used to love hot dogs, and then recently I was about to eat one at a social event and couldn't even bite it. I looked like a complete goon, took a hot dog and just put it on my plate and then threw it away—but the smell. The smell. Same thing has happened with McDonald's fries, which some in my family still love. It's hard not to gag when they hand them through the window, the smell of grease and... something... is so strong.