Is to blurt out the unsayable so that it is said and the regular conservative politicians don't have to say it. That way all the deep-hitting racist, sexist and xenophobic themes are out there and can be referred to in some simple euphemisms. These people are invaluable worker ants for the wingnut hive, invaluable.
Because what they do is bring in the dead worms from the frightening hinterlands of extremism (as Orcinus has pointed out), and they make the worms look delicious for the rest of us.
An example: Ann Coulter calls John Edwards a faggot, a pejorative term for homosexuals, a term that may have initial associations to being burned on the stake. She denies that the term is insulting at all. Then we have Thomas Friedman, a so-called liberal columnist at the New York Times say this:
"What I've been trying to do is to rename green patriotic," Friedman said. He calls it "geogreen," a more robust term than "green," which he feels has connotations of "liberal, tree-hugging, girly man, sissy, unpatriotic and vaguely French."
Geogreen, by comparison, is more "muscular" and acknowledges the linkages between global warming, the economy and terrorism, Friedman said.
See the mainstreaming of sissiness as a sign of weakness? Though Arnold Schwartzenegger first used the term "girly man" the connections are pretty easy to see.
We've advanced so far in this that my original post about "girly man" and its anti-woman implications reads totally outdated today. We are well past the point where anyone even notices that these slurs totally disempower women as political actors (not muscular enough, too sissy). All that is left is the fight over whether any liberal man can be viewed as a heterosexual man.
A postscript: Many of you, my dear and intelligent readers, don't think that I should pay any attention to the worker ants of wingnuttia, and I understand the arguments that have led you to that conclusion. After a lot of thought about it I still veer slightly towards the view that it is too late not to talk about this, and that it is more important to be aware of the reasons for the whole operation. But I will try very hard not to write about any of these things for a while...