Research has shown that most people, especially those professed lie catchers, are fooled by lies more than not.  The reason is that we want to believe the liar. We are not looking to find out that our spouse is unfaithful, that our children are using hard drugs, or the person you recommended is a cheat.  It is easy to be misled because the truth may be too painful.  The ones who proudly claim to have caught someone in a lie usually are looking to detach themselves from the person for other reasons. They are looking for a good excuse to end the relationship.
However, some are not good liars and we think we can detect the lies through the signs that they give us. Still, caution should be exercised in catching a liar. I am more suspicious of the one who proudly claims to have caught someone in a lie than I am the liar. Just for the record, research has shown that proves that several of the methods used to catch a liar are myths. For example, we have been told that looking away is a sign of lying. Research has shown that this is unrelated to lying. Fleeting facial expressions do reveal an emotion that is being concealed. However, it has been shown that innocent people who feel that they are under suspicion try to conceal their fear or their anger about being under suspicion.  I can vouch for this emotion as I have felt this way as a child when under interrogation.  You need to find out why they are concealing their emotions in order to judge whether it is a sign they are lying. Â
The fact is that nothing exists that is proof of lying and unless you can read a person’s intent, which some have no reservations about having such knowledge, there is no clear proof. Nor is there anything that is absent that gives the needed proof that a person is truthful. The polygraph, the so-called lie detector, is just a little bit better than chance, but not much.  Its use in a criminal investigation is that the person who fails is the first one to investigate.  However, investigators realize that the suspect may be the most nervous or worried about not being believed.  Truthful or not, anyone who is nervous about that will likely fail.
Scholars have noted in their writings that there are about thirty different gestures and expressions that reveal that you are not getting the full story.  What is said may, in fact, be true. But, the gestures and expressions reveal that something is being hidden. Some call these “hot spots”. Two of the most common “hot spots” are gestural slips and small facial expressions. A slight shrug of one shoulder along with a statement of confidence may be an example.  Again, other factors that may be involved is an injury, physical handicap, nervous habit, or some other element causing the shrug. Do not be too quick to jump the gun.  Another is a very slight head shake no when saying ‘yes.’  Once, again, these are not guarantees of lies.
Of course, the best scenario is that we all embrace the need to be transparent and not worry about what others may think, say, or do as a result of their newfound information.  There is nothing easy about this ideal. The only other advice to be added that will, in turn, make the first easier to do is to associate with those with whom you can be transparent.  This is part of the reason that Jesus does tells his unbelieving brothers that he was not going to the Jewish festival in Jerusalem and then goes anyway. He didn’t want to be accompanied by unbelievers when going into a city where the leaders were looking to kill him.