Well, if an orientation is obscure then it's not particularly considered apart of the community. Like Sapiosexual, for an example. Some people will try to identify with it, but it's not apart of the community for various reasons.
You may wanna re-word your title then. Saying it's obscure may come off as a bit rude if it's a valid orientation. Maybe something like, "What's a term that's not wildly known?".