Unless there is an agency which is true marketplace, open and transparent to buyers and contributors we will not have knowledge about what buyers really need. Right know most agencies keep this knowledge for themselves. Some are showing which searches produces a sale but this is rather exception than rule. Betting on generic search engines is kind of like mimic our investing companies who did not want to keep historic data for risk management and created formula which was based on current market performance of credit derivatives. When everything was going up there was a correlation :-) So I guess there must be some correlation with searches on Google but is it statistically significant?