The homebrewer's dilemma.

[jjordan]

Or "the lore and information your characters *cough cough* you players *cough cough* have encountered isn't guaranteed to be correct."

This.

Them - "Wait, wendigos can't do that!"
Me - "Says who?"
Them - "Honest Bob's Bestiary, the new official source from Littoral Spellcasters!"
Me - "You should write them a letter and complain."