It's Monday, which means we've got a Quality Score fact for you. The fourth post in our series is:
Ads may not be shown on all search results, even for queries that advertisers are bidding on. Some keywords have such low Quality Scores that ads are unlikely to show on them. Therefore, there may be keywords in your client's account that don't show any ads at all. You may want to try optimizing the ad creatives associated with those keywords to make them more specific and relevant, thereby increasing the likelihood they'll be shown. You can also find out why your client's ad may not be showing for a given query by using the Ads Diagnostic Tool.