If I can look someone in the face, can usually detect lying. Voice only, can often detect lying. Text only, can sometimes detect lying.
Is that by the same way you can divine people's true natures?
But I suppose these results (and the failings of mechanical lie detectors) are just unscientific research, which pale next to the burning truth of your subjective conviction that you "can usually detect lying".
Recently I summarized Joshua Greene's attempt to 'explain away' deontological ethics by revealing the cognitive algorithms that generate deontological judgments and showing that the causes of our deontological judgments are inconsistent with normative principles we would endorse.
Mark Alfano has recently done the same thing with virtue ethics (which generally requires a fairly robust theory of character trait possession) in his March 2011 article on the topic:
An overview of the 'situationist' attack on character trait possession can be found in Doris' book Lack of Character.