How do systems that encourage this type of play sit with other GMs?
Even if your system of choice theoretically allows it, do you play this way?
Do you prefer this type of gaming over something less game-driven?
How might you GM such a scenario differently, even if only a little?
Am I hearing an implicit "Do I know anything about a skeleton that hovers, but doesn't otherwise move?" from the player? Who then immediately assumes that a roll is required to know anything at all?
That could easily be either GM or player error, but going by Thread Title, I'm going to assume it's the system's fault. If that's the case, it doesn't sound much like a roleplaying game.
I play it like this:
PC: Have I seen this before? (or) Knowledge check!
GM: Does your background imply knowledge of such phenomena? How many points do you have in that knowledge skill?
PC: Shucks. I have one point in X skill. And my background is mostly politics.
GM: All you know is: it's a floating skeleton.
GM: (makes a behind-the-screen Detection roll for the character with the best chance to notice gelatinous shimmer or sloshing, considering both position and skill points.)
It's hard to say that I prefer this type of gaming over something more game-driven, because the player's side is ONLY game-driven. The GM's side, I suppose, is drama-driven, since he's basically ignoring the player's rolls in favor of making the encounter scarier. I'm sure there's a compromise in there, to the effect of narrating the character's thoughts (the checks of understanding) as more clues are revealed about what the thing is as is gets closer.
Knowledge checks are implicitly, "Given the current data, what do I know about this?" To do otherwise leads to nonsensical results. Let me give an example to illustrate....
GM: You are sneaking up the corridor, and see a man in a grey uniform in the middle of the chamber that opens ahead of you. His back is to you.
Player: Do I recognize the uniform?
GM: (rolls die) No.
Player: I continue to sneak to the end of the corridor, and then around the perimeter of the room.
GM: As you go, you see the man has a band on his left arm you could not see before - it is red, with a white circle on it, and in the circle is a swastika...
Ergo, the check must, to some degree, be based on what information the character has, and getting more information makes it a different test.
"A swastika? This man worships the Brahman?"
Sorry. I missed my knowledge check by 2. But I think your example helps to illustrate a problem with knowledge checks. A character, trying to figure out what he knows about something, is going to have a list of possibilities (if his intelligence is high enough. If it's low, he'll just feel dumb.) And as he gets more information, that list will dwindle. Whether the correct knowledge is in that list depends on exactly what the character knows. This last thing shouldn't be up to a knowledge check - it should be up to the GM and the player. The knowledge check should, in most cases, be a last-ditch roll for when the GM says to himself, "wow, I just have no clue if the character would know about this."
Should the PC get another knowledge check to, say, identify a floating skeleton, if he failed an earlier check? Well, if he made the earlier check, the GM has already said "I just have no clue, so let's make one roll to end the subject."