I have seen some dramatic changes due to smartpricing. It seems I have been smartpriced on and off a couple of times.
It seems like the quality score between AdSense and AdWords might somehow be corelated. I got de-smartpriced and then my AdSense AND AdWords campaigns targeted at a set of related keywords both shot up 200% overnight.
G claims there is no corelation between AdSense, AdWords and organic G results.