You are always personally responsible for knowing the rules, except when you are adviced by a tournament judge / rules official. So if someone tells you something that turns out to be bogus, you are still the one that gets punished.

If in doubt, always play an alternate ball (if possible) just as aaa suggests. And, no, that is not the same as getting two tries for the same shot: only one of the balls (the correct) are actually counted. Which one is decided by the tournament committe after the game.