Google AdWords Adds More Detailed Quality Score Explanations
Now, if you have a poor quality score, Google may share a reason. The reason can be found by viewing your keywords tab, then clicking on the magnifying glass icon beside any keyword, and then clicking on the “Details and recommendations” link. On that page, you can find out if your quality score is low due to your landing page, due to your ad copy, due to the relevancy of your keywords to your pages, and other reasons.
Here is a sample screen capture of the keyword analysis page: