Keep in mind, too, if you have a real hard-core group, that the scoreboard needs to seem like a game to them, not a war.

when you ding them, try to do it with humor and move on, don't dwell or lecture. Simply mark it, thank them for scoring you a point because you looovvvvvvve to win, and move right along, bouncing them back and forth and Rekstad mentioned.
Sometimes it just takes some tweaking and reflecting. I haven't found a group yet that I don't eventually figure out a way to make it tame them!