The Art of Deception
Some of these people are pure sociopaths, others are just deluded.
Again, the Web offers tips for both sides. If you want to do a better job of detecting lies, there are plenty of opinions, techniques, stories and guides available at the click of a mouse. On the other side of the equation, there is no shortage of discussions, viewpoints, books and articles dedicated to the art of lying persuasively. There are even online books that analyze the psychology of deception.
Will any of this make you any more likely to spot a lie (or turn you into a better liar?) Perhaps. Just don't forget that a little bit of knowledge is a dangerous thing. If you get overconfident in your abilities as a liar (or lie detector) you can bet that some wiseguy is going to clip you quickly and deeply.