How to judge whether a sentence is true or polite?

To judge whether a sentence is a joke, I suggest observing the atmosphere after the sentence is finished. If the other person talks to you normally after the sentence and jokes as usual, then you can rest assured. However, if the other person's expression is stiff and serious after telling this "joke", or even ignores what you said and shows impatience, then there is no doubt that this is not a joke, and what is more serious is that it will make people feel ironic. Of course, I don't think this will happen among excellent friends, only ordinary friends and even plastic girls, that is, duplicity. If I have any dissatisfaction with my friends, I will say it so that they won't understand me. I think it's better for two friends to talk out or quarrel when they are together, but if they don't explode, they will spoil their hearts. In short, it is still a word, and do it and cherish it.