I doubt I'm the only one who recalls the common use of Larry Johnson's expertise and sources within the intelligence community at TPM.  He was most prominently featured during the Plame/Wilson affair, but resurfaced countless other times, most recently with a TPMCafe post in January.

Recently, Johnson's proved himself to be among the worst when it comes to race-baiting attacks against Barack Obama, and today traffics in fourth-party rumors of racist diatribes from Michelle Obama as she keeps company with Louis Farrakhan:

I learned over the weekend why the Republicans who have seen the tape of Michelle Obama ranting about “whitey” describe it as “STUNNING.” I have not seen it but I have heard from five separate sources who have spoken directly with people who have seen the tape. It features Michelle Obama and Louis Farrakhan. They are sitting on a panel at Jeremiah Wright’s Church when Michelle makes her intemperate remarks. Whoops!! When that image comes out it will enter the politcal ads hall of fame. It will be right up there with the little girl plucking daisy petals in the famous 1964 ad LBJ used against Barry Goldwater.

I think Johnson's baseless vitriol speaks for itself, but I'm curious how this reflects on TPM's frequent employment of Johnson as a source, conduit for confidential sources, and expert commentator.  TPM deserves a lot of credit for its Muckraker work, but the credibility of future reporting could be in doubt if the unsourced claims of someone who's been proven to have all the veracity and none of the tact of Ahmed Chalabi persist unquestioned in the TPM archives.