Amazing replies, thanks you.
Very informative. So here's a follow up question to your point about searching a room. Are you saying here that in BW there would be something in that room if it was successfully searched?
In general, in a BW, BE, or MG game, if the players are searching for something, the GM's first question is, "so, if you succceed, you want to find one, yes?"... that's called asking for the intent. then, thinking about likelyhood, sets a difficulty. Now, if the thing sought is clearly violating the fiction (such as a knife in the muck after establishing the floor is clean polished marble free of debris) the GM reminds them of the fiction and says no. Otherwise, set a difficulty, based upon how likely it is.
Now, I've had a player search with intent that there was nothing left to find. To which, my "if you fail, something unpleasant finds you." He failed. I introduced in response a single vicious scorpion. All of 2 inches long, annoyed at the intrusion into its hiding spot of a finger or 4...
The health check vs the poison was rolled and failed, so it was a 1 point impairment on right hand for several scenes.