Just to add more confusion to the debate, we can perhaps correlate the concept of porn and art, or eroticism and art, with the concepts of love and lust, and our body's responses to them.
If art stimulates a cerebral reaction and porn merely a physical reaction, they're sort of in the same league as love vs lust. Probably by definition, although hard to define, we would say that love is a highly revered quasi cerebral response to something, and lust a supposedly less than virtuous (although generally more fun) reaction to a stimulus. This of course correlates with the highbrow reaction we have to art and the more earthy response with that nasty old porn.
I would argue that both love and lust can occur at the same time. (By saying I love to lust after women does not apply here). One can love their mate and be very full of lust (lustfull) after a couple of glasses of wine, good lighting and the room service tray is placed outside. The combination of the two is perhaps even be more fulfilling than just lusting after your secretary and nailing her in the executive washroom.
So I believe that indeed one can appreciate art and porn at the same time and perhaps both at the same time are indeed more fulfilling than looking at just art alone.
One problem I've tried to square away is my argument that lust is just a base reaction (reptilian brain) response that needs no higher thinking to be performed. Although we are drawn to it like flies to watermelon, we still, damn it, have to use our higher brains to qualify it. Is it safe? Is it legal? etc.
I've always been fascinated with the time/age problem as well. I look at a naked beautiful 25 year old woman and lust after her. I'd ravage her in a heartbeat. Would I feel the same way if I saw the same woman and she was 60. Same woman. Different illusion. What if she was 18? Yeah I jump her. 16? Hmmm.. better not. 14? Damn. Whats wrong with me. 10? Oh my God. I shouldn't even be looking. But it's the same "woman", just a different illusion.
So what I'm saying is that even with lust and with porn, although reptilian in nature, there is still higher cerebral thought processes occurring during the viewing. I guess the question is are these thought process high enough to be given the label of art.