From Ben Goldacre - Bad science
Among all these, reigning supreme, is the "zombie argument": arguments which survive to be raised again, for eternity, no matter how many times they are shot down. "Homeopathy worked for me," and the rest.
Zombie arguments survive, immortal and resistant to all refutation, because they do not live or die by the normal standards of mortal arguments. There's a huge list of them at realclimate.org, with refutations. There are huge lists of them everywhere. It makes no difference.
"CO2 isn't an important greenhouse gas", "Global warming is down to the sun", "what about the cooling in the 1940s?" says your party bore. "Well," you reply, "since the last time you raised this, I checked, and there were loads of sulphites in the air in the 1940s to block out the sun, made from the slightly different kind of industrial pollution we had then, and the odd volcano, so that's been answered already, ages ago."
And they knew that. And you know they knew you could find out, but they went ahead anyway and wasted your time, and worse than that, you both know they're going to do it again, to some other poor sap. And that is rude
http://www.guardian.co.uk/commentisfree/2009/dec/12/bad-science-goldacre-climate-change