Pelosi vs. the GOP Smear Machine

I never hesitate to rip the Chronicle when they blow it (which is not infrequently), so I figure I ought to give them credit when they get it right--as they do today, in a story on the GOP's smear war against Pelosi. Edward Epstein, probably the best of the Chron's Washington bureau, sets up the four big Republican attacks (the airplane, the Syria visit, the Samoa minimum wage exception, and the money for upgrading San Francisco piers) and systematically knocks them down. This is what journalism is supposed to do: not just blindly repeat the attacks (with obligatory denials, of course), but evaluate their truthfulness.

Of course, the story doesn't answer the bigger question: why any news outlet still prints anything those guys say. It's been pretty well established that if a story comes from the RNC (or from some GOP congressman's press office, or from some surrogate like Drudge) there's a 100% certainty that it'll be 90% false. Why, then do the news media still treat these smears as if they were news?