I have been on a mission with several of my clients to establish good landing pages. Good landing pages can improve Quality Score and your rank for key phrases. A good Quality Score means Google considers your page to be relevant to the phrases used in your ad campaigns and directly impacts what you pay Google for your ads. 

This test demonstrates the real dollar impact (savings), when it’s done right.
see: Landing Pages to Improve Quality Score

Google suggests:

• Edit your keyword and ad text so they clearly relate to each other and accurately describe your landing page.
• Choose keywords that target your audience. What terms would your customers use to describe your products or services? Use the Keyword Tool for help.
• Optimize your ad text to include your keyword and a call-to-action (such as purchase or sign up).

SEO quality score, Search Marketing, SEM

It appears that attitudes on mining the lesser used, but more specific “long-tail” phrases is changing. Quality Score is making it too expensive to go after these phrases. What this means is to improve the performance and lower the cost of your campaigns you need to clear out the deadwood.

If you must stubbornly clinging to your long-tail phrases, move them their own group so they aren’t needlessly impacting the Quality Score of your other campaigns.

More on this topic here in Yahoo’s Search Marketing Blog titled:
Chasing our Long Tails.

SEM long tail, quality score, Search Marketing, SEM