Curator of Berserk
I have noticed that in the Real Life section, a lot of the examples don't seem to qualify for this trope, but rather for Confusion Fu or Beginner's Luck. In fact, I am kind of surprised that many of the examples of beginner's luck on this page are not even on either of those respective pages.
My rationale is this: Beginner's Luck and Confusion Fu are when the expert adopts a strategy that would account for and counter what a normal opponent would probably do, and their opponent defeats that prediction because they either intentionally or unintentionally do something that nobody would normally do in that situation. Too Dumb to Fool is more like when an expert tries to use a feint or deception that would normally fool most people, but the target is too simple-minded to fall for it because it goes over their heads and they decide to stick with what they were doing. Many of the examples I saw there were about an expert predictor being fooled by an erratic amateur rather than an expert deceiver being defeated by a simple-minded opponent, so I feel like this requires some cleanup.
Is there a trope such as Too Good To Fool, where the protagonist is so Good, that trying to cheat doesn't occur to them?