Twenty years ago, NBC’s “Today” devoted three days of interviews to the insufferable Kitty Kelley, who unspooled baseless allegations against Nancy Reagan, like her supposed love affair with Frank Sinatra. That kind of tabloid bilge belched back up the garbage disposal on September 16, when “Today” promoted the new Palin-bashing book “The Rogue,” by leftist author Joe McGinniss. NBC doesn’t have an evidence standard when it's conservatives being gored. With liberals, it’s a different story. NBC didn’t give a second to McGinniss after he was roundly condemned by liberals in 1993 for his Ted Kennedy book “The Last Brother.” In 1996, after the Clinton White House complained, “Dateline NBC” canceled an interview with author and former Secret Service agent Gary Aldrich on his anti-Clinton book “Unlimited Access.”