I have a friend who is colorblind to a certain extent. When playing with the pale tv-colored cyclop balls, he usually shoots at least one or two balls out of order. I tell him to look at the damn numbers but he doesn't take the time on every shot. I watched him during a tournament last year where he got beat 7-4 because he shot the wrong ball 3 or 4 times throughout the match, giving his opponent (a weaker player) ball in hand too often. It was ridiculous that he just wouldn't take the time to check the ball numbers. I told him anyone who commits the same foul over and over again deserves to lose.
