Wow, that's absurd! Why did you let it run for 1M impressions?

We were putting together our own ad distribution system and I just needed to temporarily fill the empty leaderboard space on our website.

1M impressions generated less than $10.

How did that affect your bottom line (assuming you were also showing text ads)? Obviously the eCPM would have fallen drastically.
Did your Earnings per Click on the text ads also drop?

assuming you were also showing text ads

No, we were only showing images as we needed to have an image in place for our direct advertisers to see where the leaderboard will be displayed. It is at the very top of the page right next to our logo so the text ads would look really bad on that page.

We had the separate channel for the ad and there were no changes to our (already low) eCPM during or after removing this channel. The eCPM for the channel was like $0.07. What a joke!

The other thing I don't like is simple: unapproved Adsense image ads can be extremely offensive and bad for your rep. Even if nobody clicks on them, they will probably see them, esp. if you position them above the fold. So your rep gets worse and you don't get paid. Double whammy!

I will never use Google image ads ever again. Text or nothing; that's it. Text works for me extremely successfully. I've been text-only for over a year.

p/g

P.S. Even if the graphics of an Adsense image ad are not offensive, it really cheapens your site when the ad is offtopic, like so many A/S ads are.