AbdulAlhazred
Legend
I tend to look at these things from a fairly cinematic point of view. The characters are at an impasse, they have no dirt. They looked in the safe, nothing was there. What would happen now? Obviously, in a fairly action-oriented genre, there would be some kind of reveal. Some NPC would show up, or another clue would be discovered pointing at the REAL location of the dirt.To answer the second question, allowing the players to declare an action - they are deliberately having their PCs look in the safe, to see if the dirt is in there - while knowing that, in fact, nothing is at stake, is not actively revealing the town in play. It's reactive, and creates anti-climaxes, and moments of "OK, what do we do now". For a game whose principles are drive play toward conflict and escalate, escalate, escalate it is - as I have posted - an error, a type of failure in play.
In an RPG scenario the first part would simply be explication on the part of the GM. The players would be directing their PCs to find the dirt, and the GM would allow that, having searched the Mayor's safe and not having found it, they encounter the Secretary, who reveals that the dirt is in the keeping of the Mine Owner, and probably some other new plot elements are developed to explain that and likely to add pressure on the characters to act on the information, etc.
At no point is it necessary for there to be an action declaration who's intent is to reveal some fact such as @Crimson Longinus is thinking of. There might be sequences aimed at convincing someone to tell of the Mayor's safe, and then again some sort of conflict with the Secretary, and maybe then this all leads to a shoot-out with the Mine Owner's thugs.