Let's take Lucky Pierre for example - it can contain mmm, mmf, fffm, mmt, mft, and a whole variety of other variations.
Should it just be under a bisexual umbrella? What about the all male or all female content? Or all trans? It doesn't fit into a clean category, but individual posts may.
So some may need to go under multiple categories with this structure.
This is trying to be like reddit's NSFW411, which used hierarchical categories. Tags would work better in a lot of ways, but that would require a different format. Ideally there'd be some way to have a hierarchical structure for tags and each comm can have multiple tags, but I'm not sure how to implement it here.