Interesting post. I think that too often people tend to get swayed by charm and a certain allure of trustworthiness that some people know to fake really well. Politicians are a fine example. But as you said, checking the background and past behavior is vital. Past behavior is a great indicator of what that person really is. Words can lure you into many traps of perception, but actions are a clear sign. I remember reading somewhere it is quite interesting to do once in a while an experiment and act like you are in a mute movie : you can't hear the words, you only pay attention to what people do. It works amazing if practiced often.
Information perceived as a truth is cluttered along the way with emotional attachment, sympathy, associations with what we believe it's right. Sometimes people, leaders, made good choices which were unpopular, unloved, because people embrace familiarity much often than novelty. Therefore they indeed reject the pain of having to let go to an idea, to admit their own failure at judging one matter. Even if they might have a hunch they embraced the wrong idea, most will follow through until the end only to not lose self esteem. Unfortunately, people fail to realize, on a mass level, that admitting one's flaw judgement and replacing with it a better one, closer to reality and truth, is not a sign of weakness, but of strenght. Of progress
Observation is key. Words can be untrue. Actions speak louder than words. The goal is maa kheru, to be be true of voice, where your words align with your actions.
The stubbornness and saving face to continue along the wrong path is foolishness. It's better to know as soon as possible when a wrong turn has been made in order to course correct the mistake, to admit "I was wrong".
The alignment of words with actions. That is quite a worthy goal to have and achieve!