europeforvisitors - 9:42 pm on Aug 25, 2003 (gmt 0)

Supply and demand are most likely out of sync. Remember that there are *many* more sites than there are advertisers. I think that the business model will be hard for Google to sustain in the long run. The hope you have is to ride this out longer than others. As others drop off you'll get less public service ads.

It's impossible to make an accurate generalization about AdSense supply and demand because AdSense is targeted contextual advertising, not the kind of RON advertising that we're accustomed to seeing from ad networks. It isn't like an AT&T ad, where AT&T buys 10 million impressions from FastClick, Burst, or Tribal Fusion and the impressions are divvied up among all of the ad network's sites. Depending on the keyword, there may be extreme demand for AdSense clicks or there may be none at all.

If a site is getting a lot of public-service ads, it isn't because AdSense has excess inventory (there's no such thing as excess inventory with a CPC campaign). It's because the site's pages are on topics that don't attract AdSense ads. Not all content sites are equally suited to a program like AdSense. If you've got a site about French medieval poetry, you're likely to see a lot more public-service ads than you would if your site were about cruising, digital cameras, financial services, or weight loss. On the flip side, if your site deals with a topic that has great e-commerce potential, you may never see a public-service ad on your pages.