I think porn has this effect on the mainstream viewer too. Like what we see in regular movies, it will affect fantasies and expectations. That's not necessarily a bad thing. Where I do think it may be detrimental is among young folk for many of whom it's their only form of sex education. And they watch it so young. Some years back I remember a female stand up comic making a joke, "Do you do anal on a first date?" It was funny because it was outrageous. Unthinkable then. Nowdays I think it may well be part of many young men's expectations, and many young women may well feel that it is a 'normal' part of sex. On the other hand... maybe it is... One thing about the porn industry is that, like in many areas of entertainment, there is a drive to do something new, something outrageous, to keep pushing the envelope, so what was a bit extreme yesterday is the norm today, and that then feeds into what the rest of us actually expect and do.