There is speculation that google_ad_host is the publisher ID of Google’s Blogger that will take a cut of advertising revenue share from displayed ads impressions and clicks. Thus, there are bloggers at DigitalPoint forums who accused that Blogger commits cheating or stealing as the service agreement or terms does not specify that any possible revenue sharing by using the AdSense widget.
In actual, the part that google_ad_host is used for revenue sharing is true. But rumor that Blogger is taking a part of ads revenue earned is simply invalid, correct at least up to the time of publishing. Case study on Blogger confirms that it’s using Google AdSense API to provide the AdSense snippet on users’ blogs. Google AdSense API features a Revenue Share Program where developer can keep a percentage of revenue between 0% to 75% include from publishers’ earnings. But nothing to worry about reduced earning for publishers using Blogger service yet, as Blogger is taking 0% from you - that’s right, 100% of ads money generated from your impressions and clicks belong to you (less Google share, which you have no control anyway).
How to prove that Blogger is not stealing your money? Simply login to your Google AdSense account, then go to My Account tab, and click on Account Access link. You can see all third party service (such as Blogger) that you granted access as host to your AdSense ad code and reports in order to provide you with AdSense account management through their site. From here, you see that the Revenue Share Rate for Blogger site is 0%.
From the FAQ, Google AdSense API also states that you will receive an notification email if there’s any change to revenue share percentage rate, and third party services are also required to clearly display to your publishers the revenue share that you retain as well.