caribguy - 5:28 pm on Nov 23, 2008 (gmt 0)

Summarizing your post, please correct me if I get it wrong:

- the type of ad media (text/banners) does not make much difference re click through rate
- google regarded those clicks as unpayable (why, fraudulent?)
- your second advertiser (an openex customer?) complained about no conversions
- you are unable to analyze the source of these clicks because of the 3rd party ad delivery method

If these are 'real visitors' could they possibly have an incentive -get paid- to click, perhaps in an automated fashion? What about the other 95%

Like BriGuy said, you can serve an affiliate ad in that position. Use your own server to display the ad and to redirect the clicks. Analyze the results...