Even today when I speak about info security they look like you're wearing a foil hat. Another scam is people knocking into doors to "deliver useful social information" and asking for your ids/signature in the end. It may be marketing info collection or even simply visual wealth evaluation, but sure there are those who believe it's done for good [edit:] intents.

I'm usually let them tell their tale (out of my room, of course), ask a lot of questions, nod with them happily, and in the end I say thanks, but I'm sorry, I don't disclose my info, full stop. Their butthurt is sometimes too cool to watch without popcorn.