It appeared that the best answer to the question of how to handle it is to simply look inside oneself and ask if it's something you might do. It's not really very easy to stop (no pun intended) others from doing. Perhaps it is more about hoping that karma simply catches up with those who think this behavior is acceptable to win. Sometimes, we have look deep inside ourselves and know that we play the game the right way. We have to rely on our inner peace and not our competitive juices to control us. When we do that, the truth usually shines.
Of course, if you can, sometimes the best revenge is to just keep your mouth shut and get the victory yourself...legally and with class.