The Paradox of Decency
The concept of decency: That there is a way to behave around others which is fair and proper in respect to others, which shows respect, and allows others to be themselves.
The paradox: While being decent, it is not possible to point out when others are not decent, because doing so by definition exits the realm of allowing others to be themselves.
Therefore, a decent person has no chance to help others discover their own lapses in decency.
Simple, yet perplexing. While it may sound old-fashioned, I think this is a far more proper method of operation. The offending person will either eventually recognize their problem and overcome it, or they will continue on being a lout.