From Urban Legends:
The TV business is uglier than most things. It is normally perceived as some kind of cruel and shallow money trench through the heart of the journalism industry, a long plastic hallway where thieves and pimps run free and good men die like dogs, for no good reason.
Which is more or less true. For the most part, they are dirty little animals with huge brains and no pulse.
Exact quote. The full piece, clearly lambasting the business of TV journalism, was originally published as a bylined column in the San Francisco Examiner on November 4, 1985. It was not about radio, it was not about the music industry, it was not about show business in general nor about the corporate communications industry (though for all we know Thompson might well have agreed that the characterization fits equally well in every case). It was about television. Period.
As for the phantom tag line (“There’s also a negative side”), it’s nowhere to be found in the original article. Nice joke, but Thompson didn’t write it.