In one e-mail from 1999, the center's director, Phil Jones, alludes to one of Mann's articles in the journal Nature and writes, "I've just completed Mike's Nature trick of adding in the real temps to each series for the last 20 years (i.e., from 1981 onwards) and from 1961 for Keith's to hide the decline."
Mann said the "trick" Jones referred to was placing a chart of proxy temperature records, which ended in 1980, next to a line showing the temperature record collected by instruments from that time onward. "It's hardly anything you would call a trick," Mann said, adding that both charts were differentiated and clearly marked.
Mann is certainly right: "trick" is a word scientists use all the time to mean a clever way to refocus a problem or transform it somehow to make progress. If I had a dollar for every time I heard a professor say "Now here's a trick you can use," I'd be able to buy a Lexus.
An elementary example of what might be considered a trick is converting from Euclidean (x,y) coordinates to polar (r,θ) coordinates where a calculation simplifies. A more complicated example is dimensional regularization in quantum field theory, where, since some observable factors are calculated to be infinity, you instead do the calculation in 4+d dimensions and then in the end let d go to zero, and the answers are finite. (No, there is no good mathematical basis for this, as a mathematician will tell you, but as a physicist will tell you, it works.)
Skeptics who are focusing on this particular word just do not understand some of the inside language scientists use.