Depends on the interest, of course, and the angle. Rainsticks aren't an interesting topic in my mind, but if you were to talk about some broader aspect of it (mythology, for example) it might interest me (as opposed to talking about diameters and lengths - which would probably bore me to tears). This has been my experience talking about special interests with my NT family, too. If I want to talk to people about my obsessions, I need to come at it from an angle that they can appreciate, which means it should be broader, if not specific to their own interests.
It also depends on the person. I know of some members here whose interests are a far cry from my own and highly specific, but I still enjoy reading posts about their obsessions. That might be because of the way that they talk about a subject (enthusiasm, pedantism, etc.) or simply because I like them personally. Or both.
I've often thought that we need a "special interest" subforum, where we can make blockier posts about our obsessions and members can come in and engage with each other by talking about those interests. We've had a few such threads in Random Discussion, and frankly, I'd like to see more of them.
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I have not the kind affections of a pigeon. - Ralph Waldo Emerson