In response to a recurrent discussion in the author blog -- do you code for something that occurs in minor form to warn those squicked by it when those attracted by it will be disappointed?
The advanced-search option allows the reader to put in tags to avoid. Why not let authors enter tags in a section which only appears there. So, if I have a 100-word anal scene in a 40,000 word story, I can warn those turned off by anal without those wanting anal to see that tag.