I played a game once, with friends, where we had to inject as many double entendres into a normal conversation as possible, without letting on to the other people present.
What we found was that virtually every word we uttered could be construed as louche - it's not what you say so much as (wink, wink, nudge nudge) how you put it.
The point is, sex can permeate every situation, and when you're writing erotica you're wearing lewd-tinted glasses. I'm thinking about the setting for the next book, and wondering if botany can be remotely construed as sexy. There's mud, of course, which could be good. All that heavy toil can work up a sweat.
The sticking point, I suppose, is the characters. Bob Flowerdew on Viagra. It's a strange and disturbing image...