This is so true bc I work for an agency that calls customers to sell vacation getaways and we do not call anyone on the DNC list and if asked not to call them again we put them on our list immediately.
This number started calling me after I was looking online for supplemental health insurance - like, about five times a day, early in the morning when I'm sleeping, rudely and relentlessly. I finally decided to answer the phone today to say I'm on the Do Not Call registry, but then they identified themselves as some sort of health insurance agency. After a moment, a professional sounding voice (I couldn't tell if it was recorded, or real, but it was American; no accent) asked me if I was interested in supplemental health insurance, to which I replied affirmatively. The voice - or recorder - then asked what kind of insurance I presently had, and when I told them, the voice simply said "thank you," and hung up on me! Not only are they pesky, but this also felt like an invasion of my privacy.