Define "fake"

I am as amused as anyone by Stephen Colbert's latest stunt -- talking the National Portrait Gallery into temporarily hanging his portrait, over the water fountain between the bathrooms -- but after reading the lead of this Associated Press article, I wonder: In what sense is Colbert a "fake TV pundit"? Put another way: Are any TV pundits less fake than Colbert? Or are the others more fake, because they expect to be taken seriously, even if their shtick is as fact-free as Colbert's?