According to the porn stars it is mostly fake. They tune out the acting to the point where when they are done that they almost felt nothing. Many of the others (short careers) are so high that they couldn't feel it if you hit them with a baseball bat.
Over-saturation also has its effects. I think I am the only person that I know who fell asleep at a strip club. Same customers wanted me to take them to the same club about once a month. Hand them a $100 in ones. Go sit at the bar while they were at the stage seats. Once in a while the $20 T shirts that the girls would wear and then take off for them. One night I just fell asleep in boredom. The bouncer came over thinking I was smashed.
I always thought of porn as car starter fluid for couples. If you had to watch more than 5 minutes of it and didn't get started then something else was wrong.
I'm not sure what the mask comments are here. Are we talking about a Pinocchio masks?