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: Ultima Online
Demonic Spiders - Seriously, is there a magical enemy that doesn't follow the poison-paralyze-flamestrike pattern ?
Game Breaker - Many over the years, magic, plate mages, crossbows, animal taming, bards, and of course "Vas Corp Por".
Goddamned Bats - Sewer rats and slimes. They're everywhere. They pose no threat to anybody, but they tend to interrupt healing and spellcasting with their nips.
They Changed It, Now It Sucks - Very nearly everything they've ever changed. Trammel, the notoriety system, labeling potions so you can't give newbies purple ones to watch 'em blow up. Stopping potions from chain-exploding et cetera. EVE Online was originally created by a group of former players upset at the restrictions to PVP and griefing.