So I fell for this one; company offering "every dog in the Uk a free tag" to find the dog if lost. My dog is chipped but a friend posted it on Facebook and I thought well, that's a second safety net as the "finder" can scan a QR code on the tag. Sent off £3 and found that unless you activate your tag for £4.95 a month, it's useless. In order to find this out, I had to put in all my details and a picture of my dog, and only then find that I couldn't go any further and register the free tag unless I paid.
I imagine by the time this becomes well known, they will have harvested a lot of info and a lot of £3 "postage" payments, esp from stupid people like me!!