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: Discworld MUD
Goddamned Bats: Small creatures like crows and rats have very low hit points but dodge attacks rather easily. Annoying for newbies, for more experienced players, not so much.
Can be played straight with a room full of butterflies, as some of them have steel wings and can use them to slice you. Individually, they're still weak. Trying to "kill all" in room full of butterflies can be far more dangerous than taking on three armed bodyguards.