Then there is the question of how non-donors feel. The ad campaign made me negative about WP (and I bet quite a few other people).
That's an important point that is harder to reveal through A/B testing. What would Wikipedia's fundraising look like if there were another online encyclopedia that appeared to be a credible contender? Is Wikipedia Google in this space, or is it AltaVista?
Were all the advertisements the same size? (i.e. were they all images or were some text - like google adwords?).
Then there is the question of how non-donors feel. The ad campaign made me negative about WP (and I bet quite a few other people).
The third problem is the damage to the image of WP. An idiot on the top of every page begging for money really knocks the image for me.