This led to an interesting survey on "What is speculative poetry?"
Notice that there is consensus regarding the core (science fiction, fantasy, etc.) but not the fringe (surrealism, metaphor, etc.) of the content. In particular, I call your attention to the splatter of opinions about tropes, metaphor, simile, analogy, and other literary devices. Why is this so important? Because people argue over whether something is literal or figurative. I've watched this happen: "Well, the coffin is clearly a metaphor..." "No, I meant what I said. The vampire is in a coffin, floating through outer space." Doesn't get much more speculative than that, does it? Except when people don't believe you. 0_o
Now add the fact that cultural interpretation of symbols will vary widely across cultures, and one culture may have highly speculative connotations while another does not. Frex, the snake. A basic emblem of lies and death in Christian lore, the snake is a sacred embodiment of the Goddess and transformation (due to shedding skin) in Pagan lore. So for Pagans, it's more speculative because we'll think of shapeshifters, magic, and life/death/rebirth. Christians are likely to count it only if they also count religion/cosmology in general as speculative or they equate snakes with the Devil sufficiently to land it in the angel/devil subgenre that many folks consider speculative.