If someone tells you the opposite of the truth in order to deceive you, and you believe the opposite of what they say because you know they are deceitful, then you believe the truth. (A knave is as good as a knight to a blind bat.) The problem is, a clever liar doesn't lie all the time, but only when it matters.
It's more likely that they're a stupid liar than that they got it all wrong by chance.
Here's the new thread for posting quotes, with the usual rules: