how effective is the facebook advertising?

Recently the BBC did an investigation on the effectiveness of the social network as a promotional tool. Running a campaign for a fictitious business called VirtualBagel. BBC technology correspondent Rory Cellan-Jones spent $10 advertising the company's Facebook page. Among few weeks, the company's page has amassed 3,113 "likes" on Facebook. However,the BBC found that the number of "likes" in countries such as Egypt and the Philippines was out of proportion to the countries the virtual company targeted, such as the U.S. and U.K. Facebook responsed as "This doesn't represent the experience of most advertisers on Facebook. The examples that you have mentioned are really unusual and seem to be the result of some bad advertising practice.”
However, this is not a rare case. In my experience, when companies targeted global audiences, the majority of responses came from particular areas. When we distribute advertising on social network, we need to pay attention to the demographer targeting to make sure who are the people “likes” our product.