Speculative Troping is the unfortunate habit of troping based on what is "likely" within a work, instead of what's actually in the work.
Tropes Are UncertainIt most often occurs when a troper spots a Cliché and they've Seen It a Million Times. The Lovable Rogue has abandoned the heroes before the final battle, but is feeling pangs of guilt. The lead characters in a Love Triangle just shared their First Kiss, to the heartbreak of the third party. Clearly, these plot developments are going to end with the rogue going "I Changed My Mind, Kid" and pulling a Big Damn Heroes moment, and the Romance Arc is going to end with First Girl Wins! Except...those tropes haven't happened yet. Yes, these are the classic setups for those tropes, but that doesn't mean the creator intended to follow through on the trope, or that they won't change their mind, or hand off the story to a new writer, or just flat out leave the story hanging. For all we know, this is the last time the rogue will ever appear, and the First Kiss was also the Last Kiss. While many would argue that doing this probably wouldn't make for a good story, don't forget that there's a LOT of bad stories and, yes, this might be one of them.
Audiences Are UncertainIt also happens to Audience Reactions, such as when a show does something that some of its fans don't like. That doesn't mean a Broken Base is inevitable; even fans who disagree may feel that their angry kin have a point and the two may never come to blows over it. And just because the title character is NOT the protagonist doesn't mean we'll end up with a case of I Am Not Shazam. These reactions require that audiences actually react that way, and in enough quantity that they're a rule and not an exception.
Intent Is UncertainWord of God aside, there's no sure way to know what a creator intends, thus it can be hard to distinguish between this and a Downplayed Trope or Implied Trope. There's no hard line separating them, but it all comes down to how far your logic is leaping. If two characters are flirting, the Dress Hits Floor, and then the scene cuts away, it may imply that they were intimate.
But that's ALL it implies. Just because a work used one trope doesn't mean it used similar tropes. Without any other context, tropers can't just leap to other conclusions. This doesn't automatically make them an Official Couple. It doesn't mean one or more of the characters have redeemed past deeds. Heck, it doesn't even mean they ENJOYED it. The only information we can convey from that basic scene is that something naughty may have happened, but it's still only implied.
And conversely, just because a work isn't using a specific trope doesn't mean it's automatically using another one. Just because a villain isn't a No-Nonsense Nemesis doesn't mean they qualify as having Bond Villain Stupidity. The former is the antithesis of the latter, but its absence doesn't guarantee that the villain is that impractical.
Related TropesSee also Never Trust a Trailer, because trailers, previews and the like may differ from the published work.
See Creating a Work Page For an Upcoming Work, for how to avoid speculation when creating a page for an upcoming work.
May also overlap with Examples Are Not Recent, if the troper uses speculative language "This trope MAY happen in the future" or "This trope seems TO BE GOING this way". And Examples Are Not Arguable, where the example as written isn't even sure if the trope applies. Also a Super-Trope to Shipping Goggles, because tropers will see Ship Tease in any situation, even when there was none.