“Nutpicking” (nut + nitpicking/cherry-picking) means to selectively take (or “cherry-pick”) one person (a “nut”) or that person’s comment to represent an entire group. The person picked is a crazy “nut” (or “wingnut”) who clearly doesn’t represeent the group as a whole.
   
For example, a news reporter might go to a tea party political event of hundreds of people and focus on the only sign to show a Nazi swastika—thereby smearing the entire group to those viewing this news coverage of the event. On the internet, a blog might have a hundred comments, but the most deranged comment might be “nutpicked” to falsely illustrate that the blog is communist, racist, or whatever else one wants to prove.
 
“Nutpicking” was coined by blogger Kevin Drum in the Washington Monthly on August 11, 2006.
 
     
Urban Dictionary
nutpicking
The practice of sifting through the comments of blogs, email threads, discussion groups and other user generated content in an attempt find choice quotes proving that the advocates for or against a particular political opinion are unreasonable, uninformed extremists.
When Jonah has no substantive arguments for his point, he frequently resorts to nutpicking in order to demonize progressives.
by RGEsq Aug 11, 2006
 
Balloon Juice Lexicon
Nutpicking- Trolling obscure internet comments to prove that an opinion is widely held, thus proving the reverse.
 
wiseGEEK
What is Nutpicking?
The increasing popularity of political blogs and online political discussion forums has given rise to a particularly unsavory rhetorical tactic called nutpicking. Nutpicking involves an often exhaustive examination of individual posts in order to find outrageous quotes or provocative statements, particularly from politically liberal contributors. The culled quotes, often presented out of context, are meant to prove that all liberals are irrational “nuts.”

The practice of nutpicking has been sharply criticized by sponsors and moderators of many online discussion forums, but nutpicking is not a tactic easily discouraged through standard “terms of service” enforcement.
 
Wikipedia: Kevin Drum
Kevin Drum (born October 19, 1958) is an American political blogger and columnist. He was born in Long Beach, California and now lives in Irvine, California.
(...)
Career
Drum rose to prominence through the popularity of his now-defunct independent liberal blog Calpundit (2003–2004) and through his blog Political Animal (2004–2008) published by the Washington Monthly. In 2008, he took a position blogging at the Mother Jones magazine web site.
 
Double-Tongued Dictionary
Catchword: nutpicking
Filed under: English, Online, Politics
Part of speech: n.
Quotation: I held a contest to create a name for the moronic practice of trawling through open comment threads in order to find a few wackjobs who can be held up as evidence that liberals are nuts. It’s both lazy and self-refuting, since if the best evidence of wackjobism you can find is a few anonymous nutballs commenting on a blog, then the particular brand of wackjobism you’re complaining about must not be very widespread after all.…Nutpicking…I see that K Lo is busily nutpicking away over at The Corner.
Article or document title: “Political Animal: August 11, 2006” (URL)
Author: Kevin Drum
Article, document, publication, web site: Washington Monthly
Date of publication: Aug. 11, 2006
 
Battlepanda
Friday, August 11, 2006
Meme ‘o the day: Nutpicking
Something that is very gratifying about the blogs is how quickly stuff happens. It was just yesterday that Kevin Drum, working on the suggestion of a reader, saw a semantic gap that was crying out to be filled. Before you know it, a contest was held and we now have a winner:
 
Nutpicking (v.)—the moronic practice of trawling open comment threads to cherrypick nutball views, which can then be disingenuously held up as representative of your opponent’s “side.”
     
MetaFilter
Nutpicking: a rhetorical scourge finds a name.
August 14, 2006 9:58 AM
Nutpicking : It’s a new and long overdue slur to describe the increasingly common practice on the right (and yes, on the left, too) of cherry-picking random comments or hate emails to smear your entire opposition as raving nuts. The worst so far: this execrable WSJ op-ed by Lieberman adviser Lanny Davis. Can the new term (which is modeled on the success of Godwin’s Law) succeed in shaming the nutpickers? Either way, the practice is likely to become more common, especially if the “netroots” actually win some races this November.
posted by TheWash
 
Talking Points Memo
‘Nutpicking’ hits the big time
09.22.07—11:34AM
By Steve Benen
For quite a while, conservatives have embraced an annoying strategy—trawl through liberal comments sections in the hopes of finding intemperate remarks. The right then takes these comments to “prove” that the left is made up of unhinged radicals.
 
The practice has always been rather self-defeating. In fact, about a year ago, Kevin Drum came up with a sensible maxim: “If you’re forced to rely on random blog commenters to make a point about the prevalence of some form or another of disagreeable behavior, you’ve pretty much made exactly the opposite point.” Eventually, the practice was even given a name: “Nutpicking.”
 
Unfortunately, the practice seems to have spread.
 
The Boys Weekend Journal
Monday, August 02, 2010
Word of the Day: Nutpicking
I was reading through this piece about the discussion of race in traditional and online media on Nate Silver’s FiveThirtyEight.com this morning (great blog, by the way) when I encountered the term “nutpicking.” According to the link Silver provided, the term was coined “to describe the increasingly common practice on the right (and yes, on the left, too) of cherry-picking random comments or hate emails to smear your entire opposition as raving nuts.”
   
Washington (DC) Post
Five myths about the “tea party”
By David Weigel
Sunday, August 8, 2010
(...)
2. The tea party is racist.
It’s a phenomenon that some activists call “nutpicking”—send a cameraman into a protest and he’ll focus on the craziest sign. Yes, there are racists in the tea party, and they make themselves known. But tea party activists usually root them out.