Because of a pesky thing called the First Amendment, the guidelines don't apply to news organizations, which receive thousands of free books, CDs, and DVDs each day from media companies hoping for reviews. But if the guidelines don't apply to established media like the New York Review of Books, which also happens to publish reviews on the Web, why should they apply to Joe Blow's blog? Regulating bloggers via the FTC while exempting establishment reporters looks like a back-door means of licensing journalists and policing speech.
Nobody likes deceptive advertising or fishy bloggers. But I'd rather wade through steaming piles of unethical crap on the Web than give the FTC Javertian powers to pursue shady advertorial. This is one of those cases in which the government's solution is 10 times worse than the problem.