If written directions alone would suffice, libraries wouldn't need to have the rest of the universities attached. Allowing an unimportant mistake to pass without comment is a wonderful social grace. This is no small contribution. Honesty has come to mean the privilege of insulting you to your face without expecting redress.
Ideological differences are no excuse for rudeness.
If it's against state law, it's generally considered a breach of Etiquette. If you can't be kind, at least be vague. It is far more impressive when others discover your good qualities without your help. The dinner table is the center for the teaching and practicing not just of table manners but of conversation, consideration, tolerance, family feeling, and just about all the other accomplishments of polite society except the minuet. The invention of the teenager was a mistake.