In Defense of NC-17 Slash
I was interested to read Kadorienne's column, where she said that
she got alot of comments about writing PG-13 slash.  I have read and heard plenty of people say 'I skip over the sex scenes in slash stories'. They find that stories they read work just as well for them if they skim over the sex and get back to the plot. So I'm certain there is a large constituency out there for PG-13 slash.
I'll be honest here: I enjoy slash sex scenes. I read a few fandoms for series I have never seen, and in those fandoms what I'm looking for is good smut. I think porn and PWPs are fine and glorious things in and of themselves.
However, I'd like to talk about cases where the explicit sex is only a part of the story as a whole. I would like to argue that explicit sex need not be simply a gilding on the lily, or a fun additional payoff for the reader (a kind of 'bonus track' to the story), but potentially as important a part of the whole story as any other kind of scene.
One point that Kadorienne made is that sex scenes are a case of 'seen it all before', and that in an unsuccessful attempt to make them new and interesting, writers spice them up with colourful language. 
I would say that virtually *every* scene you ever read in fanfiction (or pro fiction) is 'seen it all before'. People coming to terms with their feelings for a same-sex character -- hardly a new concept. Hurt/comfort -- done to death and given CPR a zillion times. Emotional misunderstandings, kidnappings, searches for clues, races against time to deliver the plot
device, fist fights, car cases, break-ups, makeups, characters acting weirdly while under alien mind control -- none of these are original.
What matters -- by which I mean, what I personally consider important -- is whether the sex says something relevant to the development of the story and characters. For this, we don't need flowery similes, and in fact I prefer sex scenes written in the same narrative voice as the rest of the story.
Another point that Kadorienne raised is that what is hot for one reader isn't necessarily hot for another. This is undoubtedly true. However, (excluding porn, where the objective is to be hot), sex scenes doesn't have to be arousing to be good writing. As Kadorienne noted, individual kinks are individual kinks. I would say that what ought to matter in a scene is how the characters feel about the sex, and what the scene tells us about them. Good writing will allow us to understand and even empathise with their feelings, even if they don't equal our own reactions.
Furthermore, I would say that there are circumstances in which 'fill in the blanks' doesn't work, because the reader cannot always be expected to deduce what went on, and what it meant to the characters. Not all characters are self-analytical or will helpfully give us insight into their emotions by thinking about them after or before the event.
In my view, it should be no more possible to skip a sex scene and miss nothing relevant than to skip any other scene in the story.
One of the most valuable pieces of advice given to me when I started writing fanfiction was 'only put into the story the things that needs to be there -- this applies as much to sex as to anything else'.
At the time, I was agonising over my inability to write explicit sex. I found writing it difficult and embarrassing, and could just about manage a single line before I needed a large glass of calvados and a lie down in the dark with a cold, wet cloth on my forehead. (Fresh-faced, rosy-cheeked innocent that I was back then -- oh, how things have changed.) The problem
was that I had a couple of works-in-progress that I thought needed sex scenes.
On reflection, considering the advice I'd been given, I decided that they didn't. There was nothing in the relationship between the two characters in question that couldn't be shown just as well (or actually better) without it. Sex would have detracted from the rest of the story and spoiled the pacing. Fades to black and the odd touch worked fine. And the result, when finished, was PG-13 slash.
(I will admit that I have had one or two comments that they are good stories 'despite the lack of sex'. So, Kadorienne, you are not alone.)
Then I started another series of stories which turned out to require a lot more sex. They featured a relationship between two characters, one of whom is virtually incapable of communicating his feelings except through sex (and violence, but that's another column). Indeed, for a fair proportion of the stories in the series, if asked he would vehemently deny there was anything to the relationship other than sex.
Now, oddly, I didn't create the set-up specifically so I could include a lot of sex. At the time I wrote the first slash story I still found explicit sex terribly difficult to write, and I'm far too lazy to deliberately set myself up for something that much like hard work. But with those two characters it was the way the stories had to be -- it was an AU spin-off from a purely gen story which had already established some fundamentals of the characters. So I practised and, with a lot of help from my wonderful beta-reader, finally got to the point where I could write the sex the stories needed.
The development of the central relationship occurs primarily though sex. There's a variety of sex -- not just in choreography (although I try to provide variety there too) but in emotion. There's passionate sex, friendly sex, argument sex, make-up sex, bad sex, fun sex, unhappy sex, comfortable sex, desperate sex, loving sex, manipulative sex, gift sex, revenge sex, comfort sex, abusive sex, apology sex...but I won't deny that the end result is anything other than a heck of a lot of pretty explicit sex.
All that said, even in that particular series there are also plenty of fade-to-black scenes and instances where it's clear that sex happened between scenes. Other sex scenes stop half-way through, or start at the end, or are briefly described in flashback. The sex is only detailed where it says something that needs to be said through sex, partly because I still find writing sex somewhat more difficult than other kinds of scenes.
(To the annoyance of one reader, one consequence of this is that a well-adjusted, emotionally-literate f/f secondary couple don't have an explicit sex scene, because there's never any need. Their friendly, comfortable relationship is perfectly adequately explored by other means.)
However, on occasion, I've faded to black or cut in late or glossed over the sex only to eventually realise that it didn't work and the story needed the sex to be complete.
I know at least two people who have read my 'Administration' series of stories despite disliking explicit slash sex. Or rather, to be more accurate, one actively dislikes it and one simply doesn't find it interesting. I have to admit that, in a way, I find this rather strange. Not that they're don't like slash, which is purely a question of personal kink, but that they'd read the stories despite that. After all, there is a lot of sex in those stories, and simply skipping over it would render several of them very short indeed.
Therefore, I draw a lot of encouragement from those readers, since the fact that they find the stories interesting *despite* the sex suggests I must be doing something right in judging whether the sex is necessary for the story or not. If those particular readers can find something interesting in the sex scenes, then the scenes are probably saying what I want them to say.
So, in summary, while I agree PG13 slash is both possible and enjoyable, and have written it myself, I don't think that explicit sex scenes can be dispensed with entirely in all circumstances. In some cases they are the best way to convey what needs to be conveyed.
(This column has been mostly about my own writing, because that's what I feel competent to comment on -- I'm always dubious about second-guessing the motives and intentions of other writers. If anyone would like to take a look at this allegedly explicit-but-it-needs-to-be 'Administration' series, it's on-line at http://www.mannazone.org)
 I'm not saying that Kadorienne is 'wrong' in her views -- they are her personal feelings and fiction preferences and therefore by definition cannot be wrong. I acknowledge her right to write her stories any damn way she pleases, and I know that she feels the same about other writers, because she said so in her column. Just so that everyone is clear on this.
 She also raises problems with bad choreography making the scenes hard to visualise. I will just say that bad choreography is bad choreography and applies equally to sex scenes, action scenes, and dialogue scenes where
people come through the door four times without ever leaving the room.