gregbo - 8:59 pm on Jun 26, 2006 (gmt 0)

one of the points that has already been mentioned in brilliant message #106 is: there is no way to correctly track sales resulting from your efforts.

CPC is no better in this regard (from the publisher's standpoint of getting credited for delivering a user to a site). A user is certainly free to type the URL into their browser directly, rather than click on the ad. People email URLs to each other, rather than tell them to click on paid links.