There are many guides in the form of books, articles, videos, training, etc, on how to spot liars, but they are all designed to detect someone who is fundamentally not comfortable with his lying. They all rely on detecting behaviors like covering a part of the face while speaking, expressions of discomfort, that kind of thing. Those all work because most normal people know when they are lying and don't like to lie. They're doing it because they think they will benefit from it in some way, but it's not something they like doing.
But there's another kind of liar: the compulsive, or habitual liar. This person lies all the time. This person isn't lying to get out of some specific problem or achieve some defined, limitted goal. The compulsive liar lies as a habit, all the time. His lying is motivated by a fundamental feeling of worthlessness or perhaps by a feeling that other people have no value. In either case, the compulsive liar does not experience discomfort about lying so all the traditional (and fairly obvious) signs about lying don't work with this person.
It's easy to detect a compulsive liar over a period of time. The weight of inconsistencies builds up. I could accept one or two improbable stories ("I'm a French aristocrat", "I have a Congressional medal of honor", "I have a PhD from Harvard"), but when you hear a large set of such improbable stories coming from the same person, the probabilities stop making sense. Also untrue statements get exposed over time. One or two could be misunderstandings, but three or ten or fifty... that's a habitual liar.
So that much is clear. I can detect a non-habitual liar pretty easily during the interaction just by observing some of the well-known signs. I can detect a habitual liar over a longer period of time by looking for improbable stories and a weight of inconsistencies.
But this is my question: Is there any way to detect a habitual liar more quickly? I have had a few recent experiences where someone who is a habitual liar has wasted far too much of my time within a business context. Things seemed promising, and then the inconsistencies started piling up, and then I wanted nothing further to do with the person... but by then I had wasted too much time and effort on the relationship.
One obvious answer is to handle it on a business level: send an invoice as early as possible in the relationship, that kind of thing. Obiously I will apply that as much as possible. But are there some other suggestions that are outside the scope of business methods?
I'm asking this question because I'm a nice and friendly guy and it seems like I attract these guys who think they will take advantage of me. I run into more of them than most people do. I guess that's another part of my question: What might be attracting these losers to me and what can I do to change that?
Thanks for your feedback and ideas.