I love it when these things go totally wrong and misunderstand what the user has been doing. It's all faulty filtering of course, but such fun!
A week ago I had about 10 emails from "feeBay" offering me various electronic devices. I binned them for a day or so, wthout even thinking about it - then decided to try to work out what I was supposed to be looking for.
It wasn't immediately obvious, but I suddenly remembered I'd done a UK wide search for religious statuary (a friend had been asking about a mini-grotto!) For searching, I use a clustering engine. Guess what? The electronic device lists all contained the abbreviation "rc" or "RC" - "remote control"!!
The one that really annoys me, though, is when a site starts to bombard me with advertisements when I already own the software or am a hardware customer. An example would be my VPN software supplier. I went to the site about a week ago to check my account status.It's been trying to sell me the program ever since - and I have two years still to run!