FrogReaver
The most respectful and polite poster ever
I suspect most have seen something similar at D&D games.I expect the following might be slightly contentious. A fundamental part of the understanding of a shared fiction is that nothing is true until all the players at the table have accepted it as true. That even the GM is susceptible to a basic credibility test. In D&D the DM is given broad authority to establish what is true in the fiction, but this may be overridden at the table on the social level.
I have personally seen this at the table in our D&D game.
DM : This is true.
Player: What about X? How about Y?
DM: naughty word. Actually this is true.
I don't think an exception disproves the rule. If anything an exception here or there would help prove the rule.