If you like a blog that both skewers low-watt political commentary and provides an important reality check about a much misunderstood political category, read Nate Silver’s post “Independent Voters and Empty Explanations” at FiveThirtyEight.com.
Silver begins by quoting from articles by writers who should know better, including Karl Rove, all in agreement that ‘Independent voters’ hurt the Dems in Tuesday’s elections — to which Silver responds:

This is what passes for analysis nowadays.
Why did Democrats lose in Virginia and New Jersey on Tuesday? Because independent voters moved against them, say the pundits…This is true, insofar as it goes; Democrats lost independents nearly 2:1 in the gubernatorial race in Virginia, and by a 25-point margin in New Jersey.
But it doesn’t really tell us very much. It’s a lot like saying: the Yankees won the Game 6 last night because they scored more runs than the Phillies. Or: the unemployment rate went up because there were fewer jobs.

Silver then provides a reminder course in J-101:

But in politics, it’s not the proximate cause we’re interested in but the ultimate one. Yes: independents went mostly for Republicans in New Jersey and Virginia (we could have inferred this without having to look at the exit poll). Yes, this “caused” the Democratic defeats. But what caused the independents to move against the Democrats? That’s what we’re really interested in, since that’s what will have implications for future elections.
Too often in “mainstream” political analysis, once it is pointed out that independents have swung in one or another direction, the analysis stops. The pundit inserts his own opinion about what caused the independent vote to shift (“Obama’s far-reaching proposals and mounting spending”, says the Washington Post), without citing any evidence. It’s a neat trick, and someone who isn’t paying attention is liable to conclude that the pundit has actually said something interesting.

Ouch, sayeth the punditry. Now, some poly sci for grown-ups from Silver’s post:

Part of the problem is that ‘independents’ are not a particularly coherent group. At a minimum, the category of ‘independents’ includes:
1) People who are mainline Democrats or Republicans for all intents and purposes, but who reject the formality of being labeled as such;
2) People who have a mix of conservative and liberal views that don’t fit neatly onto the one-dimensional political spectrum, such as libertarians;
3) People to the extreme left or the extreme right of the political spectrum, who consider the Democratic and Republican parties to be equally contemptible;
4) People who are extremely disengaged from politics and who may not have fully-formed political views;
5) True-blue moderates;
6) Members of organized third parties.
These voters have almost nothing to do with each other and yet they all get grouped under the same umbrella as ‘independents’. But that’s getting away from the point. Independent voters are treated as a cause, when all that they really are is a symptom. The key is in figuring out what ails the patient.

If anything more pertinent has ever been said about “independent voters,” do share.