Google AdSense is undoubtedly the best advertising network out there that follows a pay-per-click advertising model. When Google AdSense
was first launched they were accepting almost all websites with over
100 content rich pages and that comply with their basic program
policies. So almost anyone was able to get an AdSense account (even with
scraped content) in less than a week or two.
But today, your website must not only comply with Google AdSense Program Policies but must also comply with Google Webmaster Guidelines.
It means that you they can deny your AdSense application if your
website is selling text links or is hosting copyrighted content, etc.
Even if your website complies with these program policies and guidelines
they may still reject the application based on the content quality.
Is It Possible To Make Money Blogging Without Google AdSense?

