I work with both YPN & Adsense. YPN continually has a lower click through rate(even when placed in the same positions as they adsense were), but higher payouts. I would love to see the click rate increase ...especially at some of these cpc rates! How can we help them figure this out :) In my case:
1. The ads aren't quite "right on" targeted.
For example: if it were a bedroom decorating page they may display Feng Shui decorating advice & Dining room table pads or safety storage cabiniets. They have to do with decorating, but not for the page they are on.
2. Ad information is cut off and is not completely readable. Some ads give only 1/2 the information ( depending on how it is read...like
"Widget Mania...Widget expert does..." and that is it. Personally not enough information.
What do you think is causing the lower click rate?