Hussar
Legend
I agree with all this.
Darkvision and poison resistance seem like elements in action declaration and action resolution rather than performance/presentation, so I'll put them to one side.
In most FRPGing, grooming one's beard, choosing one's food, not liking boat,s is all just colour. If my familiarity with the underground, or the distinctive histories or politics of my people, actually matter in play then that will come out in action declaration - as it does, for instance, for the dwarf in my 4e game.
Or to take another example: in the most recent RPG session I GMed - a Cthulhu Dark session - one of the PCs had two descriptors: head butler, and proper English gentelman. We didn't need the player to present or perform these descriptors in order to appreciate them - they were manifest from beginning to end in the play of the character: his concerns and motivations, his actions and responses.
Conversely, if the only way that I can tell your character is a butler is because you make references to the sivlerware that have no bearing on the actual play of the game; or if the only way I can tell you're a dwarf is because of your repeated references to your beard that never actually matters to any actions that your character undertakes; then I wonder what the point of the descriptor is at all. How is it actually informing the role you are playing in the game?
Hrm, so, your Butler player never references anything? Zero description. We're supposed to guess that he's a butler and proper English Gentleman by the fact that he does what exactly? The player never attempts to sound like a butler or English for that matter? Never tries to affect a different diction? Nothing? His responses in no way give any clue about what he is?