The worst and most serious type of flattery is when a person is in a position to rebuke a evildoer for his evil deeds but instead flatters the man and tells him “You are good.” Besides the punishment the person will receive for neglecting his responsibility to protest when it was in his ability to do so, the person will also be punished for the flattery itself, which is a great sin. A pure, God-fearing Jew would have no concern for his own honor and therefore would not refrain from rebuking someone he knows would listen to that rebuke. He will trust Hashem that He will not withhold good from those who walk with integrity. Whoever raises the honor of Heaven — his own honor is raised.
It is forbidden to look at the face of any wicked person who sins arrogantly and publicly. And even if one is not in the position to protest the man’s evil deeds, at least one should flee from him and not show him any respect or honor. Nor should one wish to gain any kind of benefit from such a man; instead, one should be repulsed by the man. And even if one sees that there are many people who are flattering sinful individuals, one should not be a follower of the majority for evil (Shemos 23:2). Rather, he should rise like a lion to do only what is good and upright in the eyes of Hashem, even if ignorant people do not agree with his behavior. Let him conduct his affairs with justice, in accord with the Torah, and Hashem will come to his aid.