Last week, the most-read items on the RealClearPolitics website were complaints about the "mainstream media." Basically, it was Mitt Romney supporters claiming that their man was behind in polls because the so-called mainstream media were biased against conservatives. On the left, meanwhile, the beefs tend to focus on "what the media aren't reporting" — most often plundering by big business. About 11 out of 10 times these commentators know "what the media aren't reporting" because they read about it ... where?

Let's linger on the left side for a moment. In Rolling Stone magazine, Matt Taibbi regales us on "the incredible untold story of the 2012 election," which is this: Romney's "hypocrisy" in railing against federal debt after his Bain Capital loaded down companies with debt so heavy they sometimes collapsed. Taibbi is always an entertaining read, and his portrayals are mostly accurate, even though they often make faulty connections. (Corporate debt and federal debt are two different things.)

But the "untold story" of what Bain did to companies and their employees, including the debt part, has been told about a million times. It's been told in The New York Times, The Wall Street Journal, Bloomberg Businessweek and leading newspapers from Maine to Hawaii, from Florida to Alaska. Every fact pertinent to Taibbi's thesis was revealed elsewhere in the media. It is entirely possible that many of Taibbi's readers — like the millions who get their news from right-leaning Fox News — don't spend much time reading grownup coverage of public affairs. They prefer hyper-partisan presentations and thrill at the suggestion of conspiracy. That's fine, but let's not pretend that an opinion piece relying on the reporting of others is unveiling a cover-up, unless it digs up its own information.

Last month, conservative Michael Barone grumbled that criticisms of Romney's selection of Paul Ryan as a running mate were "echoed gleefully by mainstream media." This was three weeks after a Wall Street Journal editorial, "Why not Ryan?" helped propel the pick of the Wisconsin rep.

"The case for Mr. Ryan is that he best exemplifies the nature and stakes of this election," the editorial said. "More than any other politician, the House Budget chairman has defined those stakes well as a generational choice about the role of government and whether America will once again become a growth economy or sink into interest-group dominated decline."

Is Barone implying that The Wall Street Journal — even though its circulation tops that of both USA Today and The New York Times — isn't part of the "mainstream media"? It would seem so.

In a Chicago Sun-Times column, predictably titled "Media Cover for Obama's Failures," Steve Huntley refers to "the mainstream media's obsession with what Obama-friendly commentators see as Romney's gaffes." Actually, in the days after the Republican's impolitic remark that 47 percent of Americans are moochers off the government came to light, Romney-friendly commentators on Fox News were talking about little else (and trying to swat away the negative response).

Fox News reaches more cable viewers than does the liberal MSNBC or centrist CNN. If right-wing pundits get away with routinely omitting conservative media giants in their definition of "mainstream media," what chance does a liberal editorial page that balances its views with opposing commentary have in winning at least grudging respect?

I ask myself: Why get worked up over laziness? Because the reporting off which opinion journalists make their arguments is expensive. Sure, a lot of news coverage is shoddy. Always was. But these drumbeat attacks on America's newsrooms as congenitally unfair or incompetent undermines their credibility and, by extension, economic viability. Without serious journalism, there will be no civic culture worth a damn.