Major search engines allow "negative matching," giving advertisers the ability to
serve keywords only to the eyeballs you want seeing them. This ability
allows for the best qualified traffic possible. The search campaign's ads
will not be shown for searches that are not relevant, therefore there will
be fewer click-throughs that do not convert to sales. Secondly, the overall
click-through rate (CTR) will be higher because there will be fewer
instances of searchers viewing the ad but not clicking. The higher CTR will
cause the ad to attain a higher position without requiring a higher cost per
click (CPC).
Conclusion? By simply employing negative keywords into your search marketing
campaign you have the ability to improve your position ranking and target
your audience more efficiently.
Dan Murray