"It takes one to know one" is most often used for bad or negative qualities, like being rude, selfish, or dishonest. It's usually said in a sarcastic or playful way when someone accuses or criticizes you. For example: If someone says, "You're such a liar!" — you might reply, "Takes one to know one!" This means, "You must be a liar too, or you wouldn’t notice it." While it can be used jokingly for good traits, it's mainly used for negative ones in real conversations. Follow us to speak English li