Don't feel bad for playing by the rules! Some people get sour for dumb reasons, but never feel mad because someone else dropped the ball - or played the wrong one.
I was playing in league tonight and absolutely crushed a guy that shoots a better speed than I do. I was on the hill and he had yet to win a game when I snapped a nine in, he looked at me and was visibly upset and I said (jokingly) "I didn't rack 'em"
People need to take responsibility for their own shit. Depending on the league, the peanut gallery (read bench, and more importantly captain) can remind the teammate on the table of the rules without a time-out. It's on the full team, not the dim-witted player.
Don't let some one make you feel like an ass because of their neglect to pay attention. Shut 'em up by playing a better game.
That being said, playing in league is about having fun, if your not doing that, than you aren't doing it right. League play is about community and growth of the sport, enjoy it.
Hope that helps!