Since Google’s AdSense program (which places advertisers’ search ads into content pages) was first launched almost five years ago, many search marketers have questioned its effectiveness. I remember seeing a room full of angry advertisers rip into Google at a Search Engine Strategies panel back in 2003 for the low quality and high prices of the clicks the program generated, and for Google’s then-refusal to let advertisers separate their bids on AdSense clicks from their bids on search clicks. When we surveyed European search marketers in 2006, only 6 percent said that contextual ads had a positive impact on their search marketing efforts. We heard so many advertisers complain about the performance of Google contextual ads that I even once called AdSense a ‘house of cards.’

But to their credit, once Google got the message that key advertisers weren’t happy, they started working to improve the program, and over the years have given advertisers many of they features they’ve demanded: the ability to bid on contextual ads separately from search ads, the ability to run a variety of creative formats within contextual ads, and even the ability to choose which sites they want to target with their contextual ads. As a result, I’ve heard rumblings that the performance of AdSense ads has improved quite a bit lately; a notion backed up by a recent post on the PPC Discussions blog.

The post talks about 10 reasons why quality has improved, and all of them make sense — but the two biggest have to be Google’s purge of low-performing sites, and advertisers’ ability to target (or exclude) specific sites when managing their campaigns.

Contextual ads are still a very different beast to paid search, and advertisers have to manage these campaigns separately to keep their ROI up. The PPC Discussions post points readers to a couple of guides on how to best manage your AdSense campaigns, which I’d advise marketers to read. But AdSense may finally have become what Google always wanted and needed it to be: a cost-effective way for advertisers to increase their reach (and therefore their spending) on Google.