General Motors (GM) has decided to pull its advertising campaigns from Facebook, citing that their paid advertisement had little effect on customers. The move comes just days ahead of Facebook's initial public offering.

GM spokesman, Pat Morrissey, commented that the automaker is reassessing its Facebook advertising and clarified that the review is part of a regular analysis the company conducts on spending its advertising funds effectively. "We look at this with all media outlets, we look at the effectiveness," he said. "We move money around to various outlets."

GM's announcement adds fuel to critics who say that Facebook, and other tech sites, may be overvalued. More than 50 percent of Facebook users say they never click on Facebook's sponsored advertisement, according to a recent Associated Press-CNBC poll.

In addition, only 12 percent of respondents say they feel comfortable making purchases over Facebook, questioning the effectively of monetizing the social network platform. Facebook