I mean, the same could be said of GMs that run a module without telling the table they're running a module "to keep you from looking it up", etc. Personally, I flat-out tell my players I'll be running a certain module and that I'll be considering it like jazz does sheet music. In fact, when I ran Xanathar's arc after it's release, the silent business partner to his faction was an ages-old black market syndicate headed by a mimic mafia (with changelings as their juvenile stage, tasked with learning humanoid ways via a sort of rumspringa).
Establishing that not only can anything be a mimic, but the resonant fact that said mimics were more interested in observing rather than mindlessly ambushing outright was far more paranoia-inducing than any stereotypical expectation, NGL. It wasn't long before the party was all but wishing for the wardrobe/carriage/over-large chest/ornate tome to just attack and get it over with. 🤣🤘🏼