I just simply ask them questions about any policy subject or Iraq, and President Bush, VP Cheney etc.
For example, Global Warming. Ask what temp would they like the earth to be? For how long? What about parts of the world who can now farm and could not before? Is that not good? How can one enforce mandates on the entire world?
Listen to their answer, and of course it will have no logic involved in the answer, so just keep asking, how? what? when? where?
As for Iraq and the Pres, ask, why would the Pres lie to go into Iraq? Wouldn't he know he'd be caught in the lie? Why didn't he plant WMD? Explain how his oil buddies would benefit? What was his motive? Would Blair, Rice, Rumsfeld, ect all lie too? For months and months? Why would Bush, Cheney, Rummy, Rice, Powell, all with decades in gov suddenly all go corrupt and sinister? Have any of them had histories of this behavior?
It's a process of elimination, eventually they will have no answer at all.
http://www.garlikov.com/Soc_Meth.html (lots of stuff on google too)
I am going to try your method. Sounds at least fun if I can hold my temper.