Dear Barbara: Its so difficult to teach manners to adults - you're really not teaching but only trying to enforce what they've learned many years ago and now select to ignore. However, there may be another approach. Since he also is a performer, why don't you offer to do a duet with him? It may work and he may become one of your most ardent supporters. I am suprised at my pacifistic advice. Like many above, my first reaction would be to be rude right back to the slob. My second reaction would be to be physically unpleasant. Good luck & happy chords