In the Guardian, they're talking about literary sex. Most of the writers in the article seem to agree with Martin Amis that:
[I]t's "impossible" for a novelist to write about real, as opposed to pornographic, sex anyway. "Sex is irreducibly personal, therefore not universal," he later tells me.
"It's not that surprising. Of all human activities this is the one that peoples the world. With that tonnage of emotion on it, if there is going to be one thing you can't write about then that would be it. It's a bit like why it's so difficult to write about dreams."
Well, you know what I think about that: arrant nonsense. Good sex is easy as long as a) you know what good sex is and b) you're a good writer. You just have to be brave.