Well, Matt. 5:28, 29--looking at a woman, forming a passion in your heart, adultery. The possibility of becoming addicted to it = it becomes your idol, idolatry. I can't reconcile being a Christian with looking at porn, it's quite simple. It can--though it doesn't always--lead to objectifying women or misogyny. That would sum up the answer to the question at the top of the thread.
I do think it is a morally dark gray concept, as where is the line between that and prostitution? It's ultimately the same thing, just that you, or the audience is just watching rather than participating as in prostitution. I do think there is a risk of coercion there, for women. I also think the ones who are performing sex acts are taking a considerable health risk as well, since they generally don't use protection and are having multiple partners. I mean, I take it there are specific industry rules and plenty of routine testing they do, but still...there is a lot of risk there.
That said, I think it's less objectionable if those risks aren't there, and it's just a celebration of the beauty of one person's body. As long as they're willing participants and are taking reasonable health precautions (I think they should at least be wearing protection, personally), I think to that extent it's really not such a big deal.
--sd-7