This is taken directly from akazedoktor.tumblr.com:
Someone needs to submit this to TV Tropes. I have no idea how itís done though.
The creator must hint for and against a particular pairing
The fandom must be split down the middle between those who call it canon and those who donít
The creator, for whatever reason, doesnít let on, EVER.
Result: Schroedingerís Ship Tease.
Prime example: Heavy/Medic, of course.
Arguably John/Sherlock in the new series (either that or the writers have a fucking weird sense of humor)
NOT X-Files, because they went somewhere with it in the end.
Sam/Dean in Supernatural, apparently
Anyway, the point of the trope is that the creator has to swing it both ways without ever confirming or denying. Or something. I donít know, Iíve been distracted by TV Tropes