A couple of days ago, I logged into my Google AdSense account and added my domains into the textarea box for "Allowed Sites". I was seeing too many impressions versus clicks and couldn't figure out why.

Search Only

A while back, months in fact, I used the "Who Sees Ads?" plugin to restrict AdSense ad displays to search engine visitors only. It worked well until I found out that Windows Live was using some funky search JavaScript-enhanced robot. I mentioned it in my article about reducing AdSense impressions from robots.

After doing it the .htaccess way and not liking it, I created a small amount of code and added it to my theme file that displays single pages. I also wanted to be able to cache the files and inserted some code into the Hyper Cache plugin to allow for two different cached files, one for non-search and one for search visitors.

I thought I had the problem licked until I continued seeing more impressions than searches. I have AdSense on a few blogs now and I needed to find out what was going on before it got worse.

Allowed Sites

I logged back into my AdSense account today and found there was one IP address belonging to uk.search.yahoo.com showing my AdSense ads.

If I didn't use the "Allowed Sites" option, I never would have realized that Yahoo displays the AdSense ads from their cache. How many clicks from the cache do you think I was getting before this? I doubt I was getting any at all.

Luckily, neither the impressions nor the clicks are counted when AdSense ads are served from sites that aren't whitelisted.

My Google AdSense CTR

While I can't tell you what my actual CTR is, I've been lucky enough to have it remain above 5 percent despite the added impressions. It should seriously increase now that unwanted impressions are not being counted.

I don't know why I didn't use the "Allowed Sites" option before this. Maybe it's because I never saw the problem before. I've been using the meta content of "noarchive" for the Google robot, but I haven't been using anything for the others. Looking at the percentages, 70 percent of my search visitors are from Google, 25 percent from Yahoo and 5 percent from all the others combined. Before I started using the HeadSpace plugin, the Yahoo visitors were within that 5 percent.