If you want to discuss a topic without reference to partisan national politics, I'd recommend you do so and see what happens. I expect that for the most part, if the topic is one of genuine interest, you'll get a discussion about it.

That said, it's worth paying attention to what makes certain topics seem interesting in the first place.

I discuss same-sex marriage on this site not-infrequently, for example. That's because I happen to be in one, and we often discuss relationship dynamics. I don't generally get downvoted for it.

OTOH, if I were to start talking about legalizing same-sex marriage in America in the abstract, the most plausible explanation for why I was talking about this would be because it has become a partisan political question in an election year. If I wanted to talk about it for some other reason, I would make a distinct effort to frame it so that my real reasons were immediately clear.

I would also look skeptically at my own belief that those really were my real reasons.