Anything to do with vampires. So much of the lore is implied and you are expected to have some previous knowledge of the concept of a vampire.
Although this might have spread enough that pretty much the entire world has some context. I'm not really sure.
Anyone not from Europe or North America, did you understand vampires the first time you saw a film or series involving them?
Be the change you want to see. Unless they harass you for being positive toward sw, just keep posting there. You'll never find a community where everyone agrees 100% on everything. Reminding people that hostility towards sex workers is part of patriarchal values is more useful than an echo chamber.
(I'm assuming "reddit" was a slipup)