People do have misconception about the adsense earning – as far my experienced is concerned with people on adsense they do feel that earning is dependent on the right placement – okay that might be true but its not completely true – its just a part of it.
Basically what works is the traffic that is of quality and they visited your website/blog because they have liked the content.
So, all is about quality traffic and search engine listing and then comes the right placement.
However, you first need to have right content and quality traffic to rise above the competition.
What you need to follow:
Is the google guideline to score in your seo – and current google guidelines do say that you need to have your content above the ads even if you have adsense you need to rate your content above.
Secondly, you need not have fishy or spammy backlinks to your blog/website.
You can just do these corrections and work on it. Your website will be rated high on search listing and then you will get quality traffic that would yield you high adsense income – this can be true for any other PPC program.