Yeah, but personally, I agree with the OP, that we (ie most people) do not or would not tend to define someone as being a liar just because they have ever lied, once. We might even think of them as basically honest, but for that exception. For us to think of a man as being a liar, he'd (usually, I'm suggesting) have to be a habitual liar.
Whereas if a man commits murder just once, would most people not tend to call him a murderer?
