"except it is an aesthetic disaster, and, partly, an ideological disaster (certainly wrt those parts that constitute the wilder fringes of the Tea Party)."
From what point of view? From a 1970s parent's point of view, punk was an aesthetic disaster -- but that was kind of the point, right? Assuming that you are on the left, this is supposed to offend your sensibilities and cause you to scorn the stupid teabaggers. When the rednecks hear upper-middle class liberals deriding them as stupid, that just strengthens their resentment of the "elitist" others and strengthens their support for Palin. Reveling in childish behavior, regressive ignorance and thumbing your nose at the pointy-head liberal teacher-figures is part of the appeal. It's the same as how parents hating punk made it seem more rebellious.
Ideologically, they have managed to syphon off a lot of the discontent that would have historically fed into labor movements or progressive politics, and indoctrinated the economic losers to a point where they support strange pro-corporate "libertarian" policies that are blatantly not in their self-interest. In order to win them over they really had to stoop to new lows, but from a realpolitik sort of POV I would still call it successful. I think that Scott Brown is early evidence of its success, and the same strategy may win congress for the Republicans in November.
"overt racism, physical violence, assassination threats against POTUS well up from his predecessor, and nutbar libertarianism are not a good look."
Yeah, I will admit that they are taking it to new, alarming levels, but it has happened before and become the new normal. People on the left thought the same thing about Reagan's thinly veiled racist "welfare queen" tirades at first, but then it became standard beltway opinion that something had to be done about lazy irresponsible black people on welfare, then Clinton had his Sista Soulja moment, ended welfare, scaled up the war on drugs, etc.. People on the left initially thought that Bush's war on terror, wiretapping, illegal detention, and war crime policies were totally unacceptable, but by the time Obama got in they were basically normalized. He has continued most of them and refused to delve into any of the past abuses.
I will grant that maybe this time they really have gone too far, but historically the fringe right of the Republican party has been a sign of things to come.