Over the weekend, Google AdWords advertisers began to worry when their quality scores began dropping. A WebmasterWorld thread has some of the advertisers freaking out.
One said:
yup. qs dropping here... not liking the looks of this.
Whatever it was, it last a day or so and the quality score numbers went back to normal.
I am a bit surprised. Back in late July, Google sent out a warning that quality scores should drop in the future and it is nothing to be worried about. I assume it was this but I was wrong because the quality score numbers went back to normal.
Here was another report from an advertiser when his quality score dropped during the bug:
It's a little baffling that keywords with 15-20% clickthrough rates going to pages with a low bounce rate (good user experience, relevant pages) suddenly drop in QS from 7/10 down to 5/6 and not display at all.
Forum discussion at WebmasterWorld.