All languages make use of formulaic utterances as a matter of convenience. Expressions of thanks are perhaps the most common such formulas along with greetings and leave-takings. One recent innovation in American English along these lines is the set phrase, “Thanks for asking,” especially among service personnel, in response to a client’s asking them (typically, over the phone) how they are.
A week ago Y-H-B was sitting in his cardiologist’s examining room waiting for the doctor to enter, which happened in due course. Having been asked how his children were by his patient, the cardiologist said “Fine. Thanks for asking.” Under the circumstances, the use of this formula struck one as remarkable, perhaps against the backdrop of its having been heard almost exclusively as emanating during telephonic opening exchanges with service personnel.
In hindsight, what was remarkable was the impression of insincerity created by the formula. But this is the risk attendant on all linguistic formulae. Speakers sensitive to creating the impression of perfunctoriness can either avoid them altogether; or utilize such linguistic means whereby even the most fatigued expressions can be artfully varied as a warrant of one’s sincerity.