Here is the AdSense success formula from AdSense team.
1. A content-rich page = Highly-targeted ads
2. Highly-targeted ads + Interested users = Healthy clickthrough & conversion rates
3. Healthy clickthrough & conversion rates = Success!
Source: Mike Gutner - AdSense Optimization Team
So to conclude:
A content-rich page + Interested users = Success!
It is surprising how many people cannot grok this super simple equation.
