If someone is a known liar, it would be foolish then to just assume that the truth is always the opposite of what he says, the ideal thing to do is assume that anything he says could be a lie or could be a truth, or most likely, is a mix of both, and do the work of figuring out which one is best by means outside of him.
cannot be trusted means just that, cannot be trusted, it means he is following no consistent rule, and in any case could be deceiving, could be honest, or could be partially one, and partly the other at the same time.
Truth can come from a anywhere, even a known pathological liar, even in the same statement of such a person can fact and fiction reside together.
(post is archived)