One of the things liars tend to do is respond with overwrought indignation when you call them out as liars. And usually you can detect a pattern. Like, say, a guy claims to be a war hero but a bunch of his contemporaries emerge to say they were there and his claims are without merit. Stop the smears, demands the liar. Or, the president of Russia calls him a liar and he sniffs, why I'm a decorated combat veteran!
