This one is of interest to me and makes me wonder...
For the past week or two I've been using a gmail account with the word "law" in the user name. Not sure if that even makes any difference. But what I have noticed is that an ad for a competitor has been coming up everywhere Google serves adsense ads. I was taken to a landing page for a godaddy domain and the top ad, having nothing to do with law, was for the competitor. Then I'm on an aquarium site just a few days later. While some of the ads are fish related, one large 250x250 is of the same competitor!
Unless this competitor is spending massive amounts of money to sponsor something, I'm assuming that I'm being shown ads based upon some information they are collecting about me. I logged out of gmail but those ads are still being shown everywhere. I'm wondering if it may even be related to my ip address as I used my mobile phone to view the same Godaddy ad and I've received completely different ads. In fact, all the ads I was served from Adsense make me wonder what other information is being used to serve ads since they relate to credit issues, mortgage foreclosures and other legal matters, items that I have been reviewing for my legal site but am unsure as to how and why they'd appear on unrelated sites and obviously directed towards me.