Matthew Sheffield has an interesting observation at Newsbusters. He notes that "non-ideological points are pretty much the only type of criticism that you'll see the establishment liberal press allow to be made against Democratic presidential candidates. Republicans, meanwhile, can be criticized at a personal level and on a policy level":

Think back: In 2004, George W. Bush was portrayed by Big Media as an arrogant, stupid, warmonger peddling reckless tax cut. In contrast, John Kerry was portrayed as a high-falutin' rich kid who was being dogged by false charges of insufficient patriotism. (Right-leaning arguments against a Democrat are always spurious.)

In 2000, Bush was portrayed as an ignorant doofus who wouldn't have gotten anywhere without his daddy's status. On the ideological side, he was a stupid isolationist with a fetish for tax cuts and destroying Social Security. Al Gore, meanwhile was just a robotic arrogant jerk.

Go further back and the trend still holds. Bob Dole was an old desperate sell-out pandering to the far right, Bill Clinton was just a philanderer who wasn't sufficiently liberal. George H. W. Bush, meanwhile was basically the same as Dole with the added horror of being the legatee of the fiend Ronald Reagan.

You have to go back to 1988 with Michael Dukakis to find a Democrat who encountered widespread criticism in Big Media for his ideology. That is a pretty sad fact.

And even there, I'm not sure how critical the response was from Big Media. On the one hand, the exceedingly establishment liberal Saturday Night Live's "Dukakis After Dark sketch" in 1988 (now apparently embargoed on Hulu or YouTube) had a great line from Jon Lovitz, who played Dukakis:

Well, thanks for coming to the party. That just about does it for the campaign. You know, I think the one thing that really hurt us is the fact that Reaganomics works. It really does. I mean, aren't you better off than you were eight years ago? I know I am. How about the rest of you? [ looks at his guests, who shake their heads in agreement ] I wish you weren't, but you are. You are better off. And there's no denying it. Well, I'd like to thank my guests - my running-mate, Lloyd Bentsen, who'd asked me to remind you he's still on the ballot down in Texas; Jane Fonda; Daniel Ortega; an, of course, my good friend Ted Kennedy. Good night.

But the title of the equally establishment history of the campaign by Jules Witcover and Jack Germond, Whose Broad Stripes and Bright Stars? The Trivial Pursuit of the Presidency 1988, tells you exactly how the authors thought that Dukakis was beaten, through symbolism, and not ideology.

But beyond that, I'd say that Matthew is spot-on. The media's cognitive dissonance in 2004 over the response to the early-1970s reserve activities of the two major candidates--"lying" Swift Vets, versus "fake but accurate" TANG documents illustrates Sheffield's Law perfectly.