There's an article up on Alternet, a response to Robert Jensen's book, Getting Off: Pornography and the End of Masculinity. One of the authors admits that

The actors in these films are degraded, underpaid and used up by an industry with the morals of a slaughterhouse, despite what Jenna Jameson and Nina Hartley say. The women come into the industry with the self-esteem of earthworms, histories of physical and sexual abuse, and are often plunged into alcohol and drug abuse as a way of coping with their jobs.

yet goes on to argue that porn isn't really harmful to women. How does he know? By listening to what men have to say about it. If the question would be about the potential harm of racist depictions of people of colour to the said people, would he form his opinion by polling a bunch of white people?

The truth, and it should not be too difficult to figure it out, is that if you really want to learn about harm, the best people to listen to are the ones who are the targets of it, who are made experts in it by feeling it in their own bodies. When the issue is porn, those people would be women. Here's one of them, Ginmar, who knows what she's talking about when it comes to men's hatred of women:

Take, for example, the case of Timothy McVeigh, which illustrates the way someone infected by hatred by society becomes unreachable after a while. McVeigh carried one book with him everywhere and re-read it obsessively: The Turner Diaries. By the time he discovered this book he was already an alienated, racist, sexist, white supremacist. He didn't seek out Black like Me in order to fight his tendencies; he sought out a racist tract to further indulge his racism. Like your basic woman-hating porn viewer, he was already screwed up. Unlike porn, though, The Turner Diaries was not a socially-reflective multi-billion dollar business which has to change with its customer base in order to continue being profitable. In responding to demand, the porn industry is causing sexual violence and misogyny to become normalized in society. This guy totally misses that.

Please read the Alternet article through also. The other author, Vivian Dent, has much more lucid take on the issue than her colleague.