Hmm, very interesting topic. But not everyone uses the word slash in that way. For example, I have an original fic that I refer to as being slashy, but by that I mean the main character is gay but it doesn't really play a part in the story. If I say a novel I just read was slashy, then chances are that I mean it had gay characters in it (though sometimes I do just mean subtext, but that's rarer to me). At Swim, Two Boys is a love triangle between three gay men. That's the story, not subtext. But I would definitely call it slashy. To me, slash is shorthand for gay lit or stories featuring m/m relationships or whatever. It's just easier to say.