Has anyone received this response from Google about their quality score? Historically for my account the keywords in question have had great quality scores. Thanks for your patience while I completed my investigation. After taking a closer look, I have confirmed as you mentioned that these keywords are relevant to your ads and landing page, which in theory would cause you to expect 'relevance' to not be an issue impacting Quality Score (QS). While these terms may have solid CTRs and seem very relevant, there are a few other factors included in QS that may be causing this low score. As you had mentioned your keywords being relevant to your ad, landing page, and business offerings, it is also true that the primary quality score that is given to your keywords pulls data from the keywords itself in terms of historical relevancy across all advertiser accounts, in addition to your unique performance history as well. Performance fluctuations can also impact the "relevance" area of QS, so it there has been a downward trend, this could cause QS to drop. If the keyword doesn't perform well across other accounts, and doesn't perform well for you as an individual, you will maintain similar scores. Additionally, if there had been keywords not performing in the account in the past, this is tied to the account's current performance, as seen by QS.
That message basically revealed to you the following factors when Google decides on the quality scores for any keyword. Most obviously, 1, CTR, 2, Relevancy (kw, ads, landing page...) No so obvious, 3, Quality Score of that keyword across the board (some keywords historically doesn't perform well for other advertisers, then you will often times get low initial quality score on it as well) or sometimes, Google won't even let any advertiser bid on them. 4, You account history will affect the quality score 5, Market changes, fluctuations will affect the dynamics of the changes in quality score. All the above is true, What is the QS of the keywords in question?