Latest I try to insert the Adsense into my web directory on the homepage and other detail listing page. It won't be a concern at how much I can get from, but it would be a good approach to offer more relevant resource for the directory visitors. On the other hand, for paid listing submitter, is it a factor when they plan to pay for a listing or not on those kind of web directories?
He makes a good point. It sends less traffic to the directory listings. Not that most people are submitting to directories for the traffic