Which conservatives are beyond criticism?

Ms. Lopez concludes by writing that “our time is better spent each doing our part rather than shooting at those who are doing theirs — and successfully.” This is a restatement of Ronald Reagan’s dictum to never criticize another Republican (never mind that The Gipper didn’t actually follow his own commandment). I often wonder, when this is invoked by Rush Limbaugh and Sean Hannity fans in defense of those men, why they never object to criticism of conservatives when it is Mike Huckabee or Ron Paul or John McCain or Colin Powell or David Frum or David Brooks or Ross Douthat or David Dreier or John Boehner being criticized. There is a strange phenomenon on the right whereby it is okay for certain Republicans to be criticized for what amounts to being heretics, whereas it is verboten to criticize other conservatives, because people on the right aren’t supposed to snipe at members of their own team. I’d oppose rules like that in any circumstance, but they might make internal sense were consistent characteristics used to determine ideological purity. In fact, one gets to be a conservative who must not be criticized based on some weird standard I cannot figure out, except to say that Rush Limbaugh, Dick Cheney and George W. Bush are all occasionally invoked as guys beyond criticism from fellow right-wingers, so multiple divorces, the idea that the executive possesses unchecked power in wartime, torture, warrantless wiretapping, atrocious immigration proposals and wild deficit spending are apparently not disqualifying factors.

I don’t get it.

UPDATE: Now that I think about it, the deciding factor is perhaps how much one is reviled by liberals, and how over-the-top absurd one’s most strident liberal critics are.