The Bible teaches that the way a man speaks indicates what is in his heart. Sometimes I've seen people criticized for something they said under pressure in a news conference or another setting in which they were asked leading questions trying to pressure them into saying something they shouldn't. When they did say something they shouldn't have, it got spread all over the media and other places. Then people make a judgment about them based on one thing they said rather than the things that usually come out of their mouths.
There is a difference between a "slip of the tongue" so to speak (all of us say wrong things on occasion) and a habit of speaking things one shouldn't.
Think of Donald Trump's speech. It is harsh, often vulgar, used to manipulate and get his own way, and sometimes it is even cruel. He has used it to mock others' beliefs and to tear down other individuals and even admitted that he had never asked God's forgiveness. He thinks that he can lead a good enough life so that he doesn't have to ask for forgiveness. No one can live such a life. "All have sinned and come short of the glory of God." (Romans 3:23)
But does all this really matter in a candidate for President? The Bible seems to indicate that it does. Luke 6:45 says, "A good man out of the good treasure of his heart bringeth forth that which is good; and an evil man out of the evil treasure of his heart bringeth forth that which is evil: for of the abundance of the heart his mouth speaketh." What a man speaks habitually reveals what is in his heart. If harsh and profane words, and even sometimes cruel speech, are what come out of his mouth, then that is the type of man he is. His words reveal what is in his heart, and "as he thinketh in his heart, so is he." (See Proverbs 23:7) Is that the kind of man we should be voting for to be our next President? Think about it.