Consider the "will smith eating spaghetti test", if you compare the entropy (not similarity) between that and will smith actually eating spaghetti, I naively expect the main difference would be entropy. when we say something looks "real" I think we're just talking about our expectation of entropy for that scene. An LLM can detect that it is a person eating a spaghetti see what the entropy is compared to the entropy it expects for the scene based on its training. In other words, train a model with specific entropy measurements along side actual training data.