From what appears to be Ross Douthat's penultimate post on his Atlantic blog, before his move to the New York Times op/ed page ("The Tea Parties"):
They resemble nothing so much as the anti-war protests during Bush's first term. The claim that they don't have an organizing premise strikes me as obviously wrong: They're anti-bailout, anti-stimulus, anti-deficit, and anti- the tax increases that will eventually be required to pay for the current spending spree, and complaining that they don't also have a ten-point plan for reforming Medicare and Social Security reflects a misunderstanding of the nature of protest marches, I think. The claim that they're hypocritical and partisan is a bit stronger - where were they when Bush was running up the deficit, etc. - but in fairness, many of the organizing figures were anti-TARP from the beginning, and there's something slightly odd about saying that if you didn't take to the streets to protests a $300 billion deficit you aren't allowed to protest a $1 trillion deficit. The numbers matter, surely ...
But they do have all of the weaknesses of the anti-war marches: Their message is intertwined with a sense of disenfranchisement and all kinds of inchoate cultural resentments, they've brought various wacky extremists out of the woodwork (you know, like Glenn Beck), and just as George W. Bush benefited from having opposition to his policies identified with peacenik marchers in Berkeley and Ann Arbor, so Barack Obama probably benefits from having the opposition (such as it is) associated with a bunch of Fox News fans marching through the streets on Tax Day, parroting talk radio tropes and shouting about socialism.
In those two paragraphs we may have the case for Douthat as a New York Times token conservative columnist distilled. In the first paragraph Douthat makes a gesture of standing athwart the spending tsunami and... noting that it's troubling; in the second paragraph he expresses his disdain for the grassroots conservative rabble that has been protesting this same spending tsunami. For good measure, Douthat finishes with a soupçon of hypocrisy in that last sentence, where he parrots the snark of the Washington Insider's David Weigel (see the caption below the third photo), while mocking protesters for "parroting talk radio tropes".
The handy graphic above comes from Douthat's post.