Marketers know the most effective advertising is word of mouth marketing. The smartest marketers know word of mouth works best when it's credible.
Unfortunately, trust is on the decline. The percentage of people who view their friends as credible sources of information about a brand has fallen from 45% in 2008 to 25% in 2010, according to Edelman's 2010 Trust Barometer study.
That's an alarming statistic for marketers wanting to tap into the power of word of mouth through social media