I’ve been programming and developing websites for almost a decade now but never started a proper blog with some huge traffic all this time (maybe due to lack of time and lack of interest too as i was a programmer and medical student – both like working in background instead of showing off) but now i decided to let’s show some kids what happens when professionals come in the field :D :P
I started this site nabtron.com almost an year ago with blog in my mind but for the first 6 month it kept on changing it’s structure etc to various forms without any proper target and direction. In august 2009 i started the blog with tech.nabtron.com subdomain using self hosted wordpress which gradually geared up with few posts (around 100) and a bit of traffic with almost no direct income (via ads / google adsense) . . . although it lead me to some other project offers though. So finally in April 2010 (yes this month) i decided to finally move my tech.nabtron.com blog to the main nabtron.com and integrate it with my firm official website.
Ok lots of background info lets come to the topic. Well in the begining of this year 2010, although i got very few ad 
The result was ofcourse abit more page impressions to my adsense but to my surprise the pay per click reduced very much, as low as 1/10th of the pay before i started that blog. Well obviously Google can’t go into regression so fast! so definitely it was me who was doing some serious mistake! Out of curiosity but almost clueless i started to research over this matter and then i found out one of the causes for this major drop down in the blog earning via adsense.
The cause of the decrease in cost per click / pay per click (also cost per impression) was Google Smart Pricing system. Yes! google have a system named smart pricing. What the hell is this smarty? well . . . its pretty simple yet a bit complicated system which . . . in short . . .decreases your adsense earning potential.
Ummm . . . let me try to explain it in a bit easier way. When google shows ads on your website/blog, it doesn’t simply checks your website reputation and ranking and shows the ads as per your site, rather, google checks your Adsense account and shows ads according to that account’s potential and reputation. Meaning? well it means if you have a very high reputation and very high quality traffic blog running adsense which inturn gives you very high earning per month. But suddenly you decide to start another blog and you add adsense to it too . . . and you notice . . . that your earning instead of rising up decreased far below the sea level . . . why? SMART GOOGLE – oops no – Smart Pricing system. Google noticed that the ads are being shown from the same account on a low traffic and reputation site so it automatically shifts your account to smart pricing mode and reduces the earning potential by displaying low paying ads.
So the conclusion is that don’t use adsense! . . . unless your website/blog is really popular and high traffic one! or else you will bring a drop in the earning from already running adsense ad blocks on high traffic quality blogs of yours with same adsense account.
If you think your blog/website is already on smart pricing mode and want to make it high paying one again then simply stop google ads on other unwanted blogs and websites (your own and other unauthorized ones too) other than the popular and high traffic ones and it shall return to normal mode in week or two hopefully.