In his latest column Eugene Robinson notes the dilemma Corsi's book presents Obama: not responding gives its lies the whiff of truth, but responding gives its lies wider circulation. I'd add, when their purpose is to spread a lie, either way serves Corsi's purpose because it's been proven that, psychologically, people remember the lie, not the correction, even forty pages of them.
So here's how I'd respond: with a simple statement that turns Corsi's strength, the power of lies, against him and attacks the entire Republican brand by providing a lens through which to look at everything they do: You can't trust a Republican.
For instance, Georgia stood up to Russia because they thought George Bush had their backs. Fools. You can't trust a Republican. Congress approved Mukasey because they believed him when he said he wouldn't be like Alberto Gonzalez. Fools. You can't trust a Republican. We believed Bush when he said Iraq had WMD and was working with Al Qaeda. Fools. You can't trust a Republican. John McCain said he wouldn't run a dirty campaign. Fools. You can't trust a Republican. If I were scripting a commercial here for a 529, I'd end it with: Don't be fooled. You can't trust a Republican.