From the boffins at Real Climate:
Phil Jones in discussing the presentation of temperature reconstructions stated that “I’ve just completed Mike’s Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith’s to hide the decline.” The paper in question is the Mann, Bradley and Hughes (1998) Nature paper on the original multiproxy temperature reconstruction, and the ‘trick’ is just to plot the instrumental records along with reconstruction so that the context of the recent warming is clear. Scientists often use the term “trick” to refer to a “a good way to deal with a problem”, rather than something that is “secret”, and so there is nothing problematic in this at all.
"Trick" does indeed feature prominently in the history of science. Possible past users of "trick" as "a good way to deal with a problem":
Perpetrators uncertain -- the Piltdown "missing link" fossils
Hwang Woo-Suk -- fabricated stem cell research
J. Ignatz Roderick and Johann Georg von Eckhart -- tormented an arrogant university colleague by planting fake fossils for him to find
Victor Ninov -- "discoverer" of ununoctium and ununhexium
Jan Hendrik Schön -- data fabricator and creator of irreproducible results
Dr Andrew Wakefield -- research linking vaccines to autism
The list of science tricksters is almost endless.