Public disclosures concerning Facebook do not yet appropriately address the differing sets of advertising customers and the economic/demographic/geographic aspects of their makeup. If their user base skews towards younger potential custuomers (those in households headed by adults 25 and under, or even 34 and under), then the collective and expected buying power of the community (concentrating on the U.S.) likely would disappoint potential prime advertsers. Outside the U.S., where they grow most rapidly, Facebook has yet to make money before income taxes--this is where they garnered a majority of their revenue in 2013. Management certainly has the ability to make fuller and more meaningful disclosures---good news is never hidden, while bad news frequently is.
http://www.washingtontimes.com/news/2014/nov/9/charles-ortel-facebook-owes-investors-a-little-det/