Over at B2Blog, Dave J has concerns about Google’s trial of a cost-per-action model for AdSense.
The obvious technicality is that for a lot of smaller & B2B businesses, the most common ‘action’ coming from their website is a phone call. And these are the people who also are paying much more per-click in their current PPC campaigns. Which means they have a lot more at risk for click-fraud yet cannot rely on CPA to help due to the untraceable phone call.
He also doubts whether AdSense CPA will be able to get enough volume in order to spread its reach to small B2B firms.