The Lao-ocean Girl, as always, was way ahead of everyone else on this story. I can't find her post of double-dipping, but she discussed it a few years ago.
Yahoo has an article about finding bacteria in communal dips, just in time for the Superbowl. I presume the same information applies to the shared condiments available at a Korean restaurant. My favourite side dish is dwen-jang jigae (soy bean soup) and now I know I need to either hog it all to myself, be sure to eat first or pass on it altogether.