visitors who get to retail sites through sponsored links are more likely to buy than those who click on organic results. They also spend more; the average order of a paid linker was $11 higher, at $117.06.
It suggests that
human shoppers might be turned off by the tricks that make a site show up higher in Google rankings. In particular, Google’s Web trawling software is lured by pages with lots of material. “When we’re optimizing for search engines, content is king,” Mr. Smith said. “But less is more when engaging a visitor.”
via New York Times