If you're into AdWords, and you don't read Andrew Goodman's 4 page article on the upcoming "Ad Quality" changes, you might as well being throwing your money away...
If you aren’t attuned to the concept of “search quality,” your campaigns will start to cost more than they should.
He describes better than anyone else what these AdWords changes will mean to the advertisers. Yet, you know this is all Google black magic when you read Andrew's conspicuously non-quantitive description of how it works. Samples of the hedging:
In short, I think CTR is as important as ever in the new regime. The change is more one of smoothing advertisers’ experience in dealing with essentially the same challenges.
I wonder what percent of the AdWords advertisers will understand these changes. Perhaps 5%? Even Andrew can't tell you exactly what to do about them. It seems to me that Google's opening up more lebensraum for the sophisticated ad arbitrageurs...