Sadly not. Like any other scene, they have to be worked on in the cold light of day as you stare at an empty laptop screen and try to hammer out your daily word count. I did attempt once to pen a scene purely for personal pleasure, but the results were disastrous. It's a bit like trying to write under the "creative" influence of alcohol. You race along, the words seemingly flowing like honey (steady), and then you read it back in the morning, cringe and hold down the delete button.
The biggest problem for me is bodypart nomenclature. Do you take the literal route or reach for the similes and metaphors? Either way, trouble lies.
Michael Cunningham, another of those shortlisted for this year's Bad Sex Prize, opts for the blunt language of the playground when it comes to describing the male member.
Saskia Goldschmidt, also shortlisted, prefers metaphor: "I unbuttoned my pants, pushing them down past my hips, and my beast, finally released from its cage ... " You can see the problems.
So, what to do? A purely gratuitous scene is always bound to fail, by which I mean the reader laughs out loud rather than looks around discreetly and reads on. If there's no justification for the scene other than the titillation of your readers, then it's best to cut it.
But if it's serving the narrative, or telling something we didn't know about a character, then at least the author's mind is focused, and you can judge the level of detail you include against those criteria.
Personally, I try to keep things a little opaque - I just find the sudden inclusion of bald, anatomical words very unsettling. I have written some terrible sex scenes in my time, written a whole book without any bedroom action at all (not the norm for a thriller) and pulled off one scene that I'm oddly proud of. It was in Dead Spy Running, my 2009 spy thriller, and involved something that I called "the Narcissus", an entirely fictitious sexual act.
My lead female character, Leila, an MI6 intelligence officer, was charged with seducing Hassan, a Qatari intelligence asset. She did this by dripping scalding beeswax all over his body, then moulding a very personal wax cast. She then filled said cast with water and froze it. Once it was ready, she peeled away the wax and, well, you'll have to read the book to find out what she did with it next.
For some reason, the scene worked, although one critic said there was a touch of Blue Peter about it ("here's one I prepared earlier"). It certainly offered something a bit out of the ordinary.
The only problem, for me and my wife is that our friends still don't believe that I made it up.
Jon Stock is the author of the Legoland Spy Trilogy: Dead Spy Running, Games Traitors Play and Dirty Little Secret (HarperCollins).