I got an e-mail this weekend that Adsense would no longer be serving ads to some of my sites.
Specifically, blog.matthewmiller.net and a Blog I manage for a friend. Both sites are hosted by Blogger, and when I go to the Adsense "Site Diagnostics" page I learn the reason for the sites are blocked is because of a problem with the robots.txt file.
The thing is, blogger users don't have the ability to edit their robots.txt unless they host their site themselves.
What has Blogger done? Simple, they've changed the robots.txt to reduce the search engine ranking of blogger hosted sites, and broken adsense in the process. Specifically, the Adsense Crawler is being blocked from indexing the site, which in turn causes Google Adsense to block the site, as it can no longer produce targeted ads.
Inexplicably, adds sometimes appear on this Blog, and the Adsense Site Diagnostic Page is erratic in when if it even lists blocked sites, sometimes claiming that I have no blocked sites. And yes, before you ask, I DID clear the browser cache.
Inside AdSense: Run, don't crawl, to the new Site Diagnostics page