[derryrover]

Or could it be that: It is actually possible to spot a lie, but it depends heavily on the skill of the liar vs interrogator: did they have experience with a previous lie that was similar?

People that are good at lying will specialize in bluffing professions (smuggler, conman, undercover, sales, politics, gambling) and people good at spotting lies will specialize in interrogative jobs (police, inspection, acquiring business, teacher, journalist, border control).

This is an arms race where specific interrogators may specialize in specific liars or specific type of lies. The problem appears when there is a mismatch between the interrogator vs the suspect or if the interrogator is just incompetent. Or maybe the suspect is just a awkward person, or has a guilty rest face. Yes spotting a lie is by far not 100% correct.

To now conclude that spotting lies never works is basically claiming the whole range of aforementioned professions may just as well be done by inexperienced people, so why would one then ever hire a experienced journalist or interrogator?