You can't thumb ads up or down on Pandora because Pandora didn't bother creating that feature…yet. This is a good idea, as Pandora could sell the ad ratings back to the company who bought the ad. This would give the company generating the ad feedback as to which ads are well received and which are not. read more
Not sure why Pandora would prevent thumbs on thumbprint radio; this is especially unfortunate in my case as I usually use my thumbs up history to make a list of songs / artists I might be interested in looking into. read more