Telemarketers always start their pitch by asking how I'm doing.

I always answer with, "Well, that depends on why you're calling me."

None of them ever takes the hint. I think it's because my answer is off script and, not knowing what they do, they go right back to the script.

@davidbragg I always ask: "What are you trying to sell me?"
The answer is, invariably, "Nothing."
To which I say: "Can you explain why you're being paid to sell nothing?"