To answer your question OP, not on the internet, but years ago when I was young, single and living on my own, I agreed to answer a consumer research questionnaire over the phone. The questions became more and more to do with sex. To this day I do not know whether it was a genuine research project, but I doubt it.
Result was that for weeks I was very careful leaving or entering my flat and opening the door, as this was well before the mobile phone era, so I could work out that any man who had my phone number could quite easily find out where I lived,
Fortunately, I never heard or experienced anything unpleasant connected with it, but it taught me to put the phone down on those purporting to be doing questionnaires.