Well, just from my experience and listening to others, it is pretty tricky to get any type of sexual content published and with ads. Just getting published seems to be easier than getting ads. I wrote a hub on sexual education, and they were fine publishing it, but ads have been disabled.
My case was particularly frustrating because I actually contacted hubpages and then went back through my hub to change the specific things they said were causing trouble. Ads were back up for about a month and then it was once again flagged as being inappropriate. I think that Google is always revising its methodology and it's robots are constantly crawling and re-crawling around the web, so that something fine at one point might not be fine later. Since that content is right on the border of acceptability, I don't really feel it is worth worrying about getting ads back on it.
The other thing that is important to understand is that you aren't necessarily being judged by humans. If a crawler comes across the word "spanking", they aren't going to necessarily know or care if it is in the context of pornography, a history of fetish, or a discussion about parenting.
At the same time, being that you are being judged by robots, you can talk about riding his stickshift until you fly to the moon and it won't have any idea what you are talking about. Maybe that sort of a 'creative' strategy would be effective.
As relache mentioned you should read the Terms of Service and Google's Adult Content guides, but they are really pretty vague. You aren't, for instance, going to find a list of specific words that are unacceptable. I have heard people say they have had problems even with proper clinical and medical terminology. In my case, my problem was a single phrase. That's all it took.