I have an old site directory site that I was looking at today. It has more than 100 pages indexed in Yahoo and Bing. But there are no pages indexed in Google. The odd thing is that Google Adsense ads are displaying fine and I have received adsense money from the clicks. Anyone have any idea why it may not be indexed in Google? The site is at http://www.knowledgesearch.net/
It's not odd at all, AdSense has its own crawler which checks pages carrying ads whenever they are accessed, in real time. As for your site, it's probably banned (unless you've been blocking googlebot in some way, or removed the URL intentionally in GWT).
Well, Google database has nothing to do with the Google Adsense. If you still comply with the Adsense TOS, the ads will still be fine.
Google Bot and Adsense Bot are totally different spider and belongs to different groups. They have nothing to do with each other. Since, yours is a phpld directory, it has a built it Sitemap Generator. Submit it to google and it'll eventually get indexed.
The site is several years old. I just recently noticed it was deindexed. I read someplace that google is starting to random remove web directories from their index.