I don't think that much of anything that is "choice consumption" is recession proof. However, consider this:
http://adage.com/article?article_id=133100
McDonalds sees sales increase 4.5%, same store sales up 4.7%.
Now, you would think that something like Rotton Ronnie's would be a luxury, after all it is eating out. But sometimes people move their dollars so they are spending less total from their pocket, but more in certain places.
So example, let's say that people have been going out to titty bars, or have been hiring hookers, or perhaps hitting clubs trying to pick up girls. Maybe they are spending a few hundred bucks a week on the process. Perhaps their version of saving money is instead of hiring a hooker every week for $250, they will instead buy live cam time for $100 a week. Now, in theory, your live cam sales go up, making you appear recession proof. Without the data from the hooker (she lost $250 a week), there is no way to show how the recession really happens.
So there is potential here that porn could in fact become more popular as people drop expensive "hunt for pussy" activities and just stay home and whack off to a hot cam girl or the latest XXX parody movie.
We live in interesting times, perhaps the ultimate curse.