I’m skeptical of the partisan contention that McCain did little or no vetting of Palin in advance of the announcement. Here’s an extended response from the McCain camp — according to an unidentified senior McCain strategist, the vetting

“included her filling out a 70-question questionnaire that was highly intrusive and personal. She was then interviewed for more than three hours by A.B. Culvahouse [head of the VP selection team]. There were multiple follow-up interviews. … There was a public records search and political vet. There was a private life and financial vet. Everything that has come out was known by the campaign through the vetting process.”

Because of America’s bizarre process for vice presidential selection, the safest pick for a running mate seems to be someone who has recently run for president (Obama-Biden, Kerry-Edwards, Clinton-Gore, Reagan-GWBush, etc.) If the prospective VP has not already been through the campaign crucible, the vetting has to be accomplished in strict secrecy, and the secrecy inherently limits how thorough the vetting can be.