MiraMels
Explorer
But it doesn't make sense for a DM to compare a PC's passive score to a fixed DC that he himself chooses, as a way of deciding anything. You could have done that before the game session even started. If it makes the narrative more interesting for the innkeeper to lie to the adventurer, go with it and just say so. "The innkeeper tells you that there are no bandits on the north road, but he is obviously lying". There's no need to justify your narrative choice with pseudo-mathematical numbers; there's no need to say to yourself "12 is greater than 10 so I'm going to tell the player that the innkeeper is lying".
Without rolling against the players, I it frequently to improvise an answer to a question that has no DC.
An example would be, a player asks me if their character knows anything about the ruined keep they just spotted on the horizon, and rather than just have them roll a check, i'll look at their passive history and give them some details based on that.