How SPAM Links can influence Adsense Earnings
Mid-February I noticed that the software running an Image Gallery on one of my sites was a few versions out of date. I also noticed that there was over 10,000+ spam comments on the image pages with links to all sorts of things, pornography, viagra, cheap software etc. I updated the software to the latest version, deleted all of the offending comments and made sure that this could not happen again.
Whilst I was updating the software I noticed that I had our old advertising code in the Gallery templates. I swapped those out for the new Google Adsense ad code. The Gallery was fixed on the 14th of February.
For the next 9 or 10 days the Gallery was averaging 3,500 page views according to Google Adsense. The click through ratio was great, the Gallery was now making quite a bit of money where as previously it was making none because of the out-dated ad code. The daily income on this site increased a lot, this was great.
However, I soon noticed in Mint (our stat tracking program) that almost all of the referrers to the Image Gallery were people searching the major search engines for things like illegal software and adult content. I checked the referring Google searches and soon saw that the GoogleBot had crawled the Gallery when the bogus comments and links from them were still on the pages.
Then on the 22nd GoogleBot must have crawled the Gallery again and updated its index. From the 22nd until present the average page views sit at a mere 1,200 and the click ratio is almost nonexistent. In a week the Gallery had gone from making some really good money every day to virtually nothing, all because I had deleted those comments from the pages.
The Gallery is no longer making much money because of this, but it is really interesting to note that because of a few keywords linking to spam in the comments on these pages the massive change in the CTR and earnings!
Now I understand why link farming, and spam bots entering bogus comments on websites is really big business, because it actually works. What is funny to see though is that because of these kinds of comments site owners could be earning even more money with their embedded advertising!