There are seemingly an infinite number of questions put out by the AGW deniers, but there are two major themes:
1) Using a detail to try to invalidate a whole picture. Argue from a particular to the general.
For instance, the hacked emails show that scientist are human, with the usual human emotions and failings. Surprise.
But what should impress us is that despite the intense scrutiny of the emails by the skeptics, no-one has made a case that invalidates the whole body of climate work. Even if Price and Trenberth's work were taken out of the corpus of climate studies, there are still more than enough studies to confirm that we have a serious man-made global warming problem.
This is well illustrated by the composite graph of long term temperature studies. After Mann's work was criticised (and this is what science is all about, criticism of the evidence), the approach has been reproduced nine times, as shown in the graph above.
The result is a lousy hockey stick for sure, since hockey sticks made of cooked spaghetti lack the structural integrity to deek, let alone deliver a slap shot, but it does very convincing picture of a world that is clearly undergoing warming in recent history.
Convincing, that is, except to those whose ideology prevents them from accepting the necessary policy changes that arise from the science.
Which leads us to the second theme:
2) The Conspiracy Theory.The US shock jocks are coming right out with it: The Great Global Warming Conspiracy, which runs like this: Gore, Soros and a few others (including, in some versions, George W Bush), in collaboration with unnamed socialists and greenies, have paid scientists to manipulate the data in order to generate a false picture of global warming so that they can achieve World Government.