>>17074386
That people are generally quite bad at it.
Most of the cues pop-culture regurgitates as signs of a liar apply primarily to children and do not generalize well to a confident adult.

If you want to get away with a lie, tell it confidently and people will generally believe you. If you want to tell if someone's lying, forget the dumb "tricks" and just focus on what they're saying and work out if things add up.