Yeah, it would be nice to have them separated... but it's really impossible due to the insane amount of threads.
I've used the thread subscription features to my advantage in this case: made a separate folder for fetishes and put all of the interesting fetish threads there whenever I find one and the babes in another folder. It will keep them in check at least after you find them. Nothing to be done for making them more findable though, except maybe tagging all the fetish threads accordingly. Then at least a tag search should find them properly. But that's an insane amount of manual work too... there's no escaping that, no matter what. There's just no easy way to get really clean search results.
Using the Google site search for the board helps sometimes when the internal search engine fails to find what you're looking for but unfortunately it will then search from all forum sections, so there will be clutter in those search results as well.
Edit: In case you don't know what I mean by "google site search", here's an example: go to google and type "catsuits site:board.freeones.com". The site: parameter limits the search to this board.