One good reason not to touch things when riding public transporation, (or anything in public for that matter). People get snotty, and when they have no manners, nor any cares, they wipe fling it on everything. This I witnessed on my way underground this afternoon, catching a train home for the day. One man walking next to me, had a huge, fatty-fountain of snot hanging from his nostril and he was blowing it out as hard as he could, seriously, Tarzan could have swung from it and reached the tip top of a tree. This mega-snot was about a foot or so long and eventually the guy ripped it off and flung it on a door, a door that thousands of transit users go through, and probably touch every day. Um, eeEEWWWWW!