Originally Posted by
navjottomer
I've also done some testing on this (though my testing is not totally exhaustive and results can vary ).
Look at it this way - Google does not make a quazillion dollars a day by showing ads that don't get clicked on. They have some very clever algorithms which (almost always) show whatever will make them (and you in this case) as much money as possible.
So I contend - that you can spend a hell of a lot of time messing around with the settings - but 99% of the time you are better leaving them at default and letting Google decide what works best...
It was a year ago when I decided to test the combo of text + image/media/flash Google Adsense ads on my websites. I just use text before the testing. I tested it for a month and my Adsense earnings doubled. So for my experience, using text + image/media/flash combo produced a better result knowing that Google now allows advertisers to create multimedia/video/flash ads.