"How is everything for ya today?"
(Although I recently got, "Is everything tasting good for ya today?" To which, I wanted to reply, "Yes, my taste buds are functioning well for me today. Thank you for asking today.")
The thing is that I almost never tell the truth. Unless something is raw or rancid, I won't give real feedback. My canned answer (most of the time spoken with a full mouth and only fleeting eye contact) is, "Great, thanks."
I don't reveal, "This vinaigrette tastes bottled," or "You skimped on the shrimp," or whatever it is that I am actually thinking...and and whatever has already influenced my decision of whether or not I'll return for a future meal.
For restaurants, is the question simply a way to build the customer relationship? Small talk while facilitating drink refills? I wonder what kind of data comes from this inquiry? Is there a missed opportunity here? Could changing the question help create a dialogue with customers? Help customers share what they are thinking about "how things are tasting." Help customers share precious info with their servers -- before they get home and post candid comments to Yelp? (As I do!)