Google just updated its AdWords Quality Score factor the other day. While the update “should affect a small number of AdWords advertisers” as Google claims, a post in Search Engine Roundtable showed that the update has adverse effect on the affected. This was discussed in DigitalPoint and Webmasterworld threads.
It is difficult to tell what were the changes if I don’t have an idea what type of sites were affected and the type of content they produce. Quality Score is a more transparent version of Google’s search algorithm. Unlike for natural searches whose Google algorithm isn’t disclosed, Quality Score is based on a set of criteria that Google publishes on its Help Center and whose updates are described in detail.
I guess that should be the case for a service that costs advertiser money.