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I would define 'porn' as any material (written, visual, aural, etc.) meant to stimulate sexually for recreational purposes. And I'm afraid some feminists are on record as suggesting that porn is either always based on the exploitation of porn stars, or then intrinsically demeaning and exploitive to women--that was Wendy McElroy's claim in her book XXX, at least. If I understand correctly MacKinnon's arguments in her Antipornography Civil Rights Ordinance, pornography is by its own nature a violation of women's civil rights, and any person who felt wronged by it was entitled to sue either the provider (e.g. the sex shop) or the author of the offending material. This because the definition of 'violent' or 'demeaning' was sufficiently abstract to encompass a very wide range of porn, some of which being, from a liberal viewpiont, perfectly legitimate.
I agree that this was a minority view--and as you well point out, AKA Smith, feminism itself stopped this view. I think we could all agree that coertion and violence should be also punished in porn--so people who are forced to work in porn, or whose work in porn is stolen and sold without their consent, etc. should be protected by law. But 'violence in porn' is sometimes seen as including e.g. BDSM and D/s porn, which in principle is also legitimate--after all, it's just a form of sexuality (one I actually enjoy myself). The discussion often gets difficult and muddled here.
(To Dick Dworkin--I don't think anybody is saying feminists could, or should, have destroyed pornography if they had united. The arguments would still be the same, and the decision would still be in the hands of judges who, especially in the 80's, were not really feminists. I think it would again be more religious right and conservative views winning, if it had happened--your cousin Dworkin and MacKinnon did have to forge an alliance with them, as I recall.)
I don't know for sure about Max Hardcore--I never watched any of his movies (I am not turned on by women who pretend to be under the age of consent, and he looked like the kind of guy I don't really like, in life or in porn), and I don't know the case (obscenithy, it seems? what's the current legal definition of obscenity?)