Adon Network Full of Clickfraud?

We have a client at my dayjob who recently purchased a little over 7000 clicks from the “keyword-targeted ad network” AdOn. They were initially impressed by the sheer volume of traffic generated and then subsequently underwhelmed by the performance of said traffic. In the process of some conversion analysis using Clicktracks today I discovered that of the 7200 clicks that came from AdOn properties, 99% immediately left the site with an average time on site of 1 second or less. This screams clickfraud to me. I scanned the raw logs to make sure these weren’t all from the same IP and they weren’t, but still, a 99% bounce rate?
I’m not yet sure how much our client spent on these clicks but whatever it was it was a complete and total waste. Does anyone else have any experience working with these guys?