These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Silent Hunter Series
Goddamned Bats: Aircraft, especially Allied aircraft. Sure they start off as a joke, but by 1944 they can spot you beyond visual range with radar, appear out of nowhere and stick a bomb right on your conning tower on the first pass. The only thing you can do is hit 'crash dive' and pray. And they're everywhere.