I do not deal with Holocaust deniers, creationists who deny evolution, or those who say the Bush Administration [did not lie]. All three of these positions are intellectually dishonest, and I will not give them the credibility they desire by "arguing" with those who claim otherwise.
The simplest way to deal with these kinds of fabulists is to take the legs out from under them. Repeat the facts, call any attempt to either dismiss or otherwise deny their credibility a tissue of lies, and move on. If those who are attempting to create an argument where none actually exists persist, like the instructions on a shampoo bottle state, "Lather, Rinse, Repeat". It's that simple.