I'm not trying to imply I will lie to the characters - just that I will make it that I'm not giving the players metagame knowledge and then trust them to pretend they don't know it. Essentially you're right - the vision I describe will be weird, symbolic, and ultimately fluff so that the person with the vision - if they fail to interpret it - can start claiming rediculous things if they roll low. If they roll high, then they can interpret it correctly and start claiming ridiculous things that are actually true.
The best part of this is it works well with the idea of sliding difficulties - they're never quite sure how well they did. If they roll terribly they might just get a nightmare vision and simply know something important is gonna happen. If they roll badly, they can get a bit of facts that may or may not be misleading. If they roll adequate, they can get the correct meaning, and if they roll excellently they can be absolutely sure of the vision and possibly even place an aspect on the vision for use later - such as knowing just where to stand to avoid getting shot, or getting even more, unnecessary info.
I should mention again, so I don't mislead you. In this situation, I'm not lying to my players, just not telling them exactly how well they succeeded. You'd give vague answers at this point unless they rolled extremely well or extremely badly.