Most of the porn scenes are full of staged expressions, moans, fake pleasure and overreactions.
I will be uploading here some parts of natural behaviour. You can find these kind of expressions often on first timers and that includes feelings such as:
-Nervous
-Fear
-Pleasure
-Pain
-Overwhelmed
-Shock
Most of these raw emotions bring a lot of intensity to the scenes and makes them quite unforgetable.