Why do people persist in treating Rush Limbaugh as if he isn't a dishonest fool?

Several days ago Rush Limbaugh uncovered another liberal conspiracy (transcript via Media Matters, bold emphasis mine)

RUSH LIMBAUGH: Have you heard, this new movie, the Batman movie -- what is it, the Dark Knight Lights Up or something? Whatever the name of it is. That's right, Dark Knight Rises, Lights Up, same thing. Do you know the name of the villain in this movie? Bane. The villain in the Dark Knight Rises is named Bane. B-A-N-E. What is the name of the venture capital firm that Romney ran, and around which there's now this make-believe controversy? Bain. The movie has been in the works for a long time, the release date's been known, summer 2012 for a long time. Do you think that it is accidental, that the name of the really vicious, fire-breathing, four-eyed, whatever-it-is villain in this movie is named Bane?

[...]

LIMBAUGH: Anyway, so this evil villain in the new Batman movie is named Bane. And there's now discussion out there as to whether or not this was purposeful, and whether or not it will influence voters. It's going to have a lot of people. This movie, the audience is going to be huge, lot of people are going to see the movie. And it's a lot of brain-dead people, entertainment, the pop culture crowd. And they're going to hear "Bane" in the movie, and they are going to associate Bain. And the thought is that when they start paying attention to the campaign later in the year, and Obama and the Democrats keep talking about Bain, not Bain Capital, but Bain, Romney and Bain, that these people will think back to the Batman movie --"Oh yeah, I know who that is." There are some people who think it will work. There are some people think it will work. Others think -- "You're really underestimating the American people who think that will work."

Limbaugh concluded by saying that, "I'm just telling you this is the kind of stuff the Obama team is lining up."

Ok, this is moronic on multiple levels. First, please note the juvenile attempt to demean the film by pretending he doesn't know what the proper name of it is ("Dark Knight Lights Up or something?"); the sort of put-down you might expect to hear from some adolescent middle school student, but not the favorite adult voice of a political movement.

Secondly, please note that, as is routinely the case, Limbaugh is ignorant about the subject matter he is pontificating about. Bane, the comic villain, was created in 1993 by conservative writer Chuck Dixon who considers him to be "an Occupy Wall Street type." Although Bane is not as iconic a Batman nemesis as the likes of the Penguin, Riddler, or Joker (neither was Ra's al Ghul from the first film) he is perhaps the most significant Batman villain of recent times in that he is the only one to have literally broken the Batman and ended his career. Director Christopher Nolan, drawing on the darker and better elements of  the Batman books, would find in the Bane-unleashes-havoc-on-Gotham storyline a very obvious way to bookend his Batman trilogy.

Again, you have the juvenile attempt to demean the character by describing him as a "fire-breathing, four-eyed, whatever-it-is villain." Limbaugh proudly wears his ignorance on his sleeve. He doesn't know who or what Bane is (Bane in the film doesn't wear a mask with eye-slits as he does in the comic, so where in the world does the "four-eyed" insult come from?).

And lastly, the parts I've bolded where Limbaugh clearly asks his audience to consider that Bane was chosen deliberately so that the Obama campaign team could negatively associate the movie villain with Mitt Romney's history at Bain Capital. Right, so several years ago, when Nolan and producers, and Warner Brothers were deciding what villain to use in the film, they knew that Mitt Romney would win the Republican presidential nomination and would make Bain Capital a centerpiece of his campaign, so they chose a villain who has nothing to do with venture capitalism so that the Obama campaign would be able to compare Bain Capital to the Batman villain Bane because the names are homophones. As one commenter I saw on the internet noted (I can't recall where), Limbaugh might next accuse the dictionary of being a liberal conspiracy planned in advance, since it defines "bane" to be something that destroys or brings harm and misery.

But as ridiculous as this all is, it's not where Limbaugh hits bottom. No. He hits bottom when after he was called on his idiocy, he denied saying what he said.

Everybody’s out there running around saying I got this giant conspiracy theory that the Batman people, the creators, the comic book creators, created this thing to campaign against Romney. I never said that. I didn’t say there was a conspiracy. I said the Democrats were going to use it, which they are.

Rush Limbaugh asked his audience, rhetorically, if they thought it was an accident that the character was named Bane and that the movie's release date had been scheduled for summer 2012. When commenters pointed out Limbaugh's ignorance by noting that the character was created and named in 1993, he lies and asserts that  he was only saying that "Democrats were going to use it." But Limbuagh, pathologically dishonest idiot that he is, can't even keep that lie coherent within a single broadcast, as later in the transcript he says

I was talking about Hollywood, the people who market the movie, who determine when it's gonna be released. So you've got the villain named Bane. We know that Obama is doing everything he can to discredit Bain.

And this is the same level of maturity and dishonesty and ignorance and incoherence that Limbaugh brings to bear on virtually every single subject that he talks about. As when he maliciously attacked Sandra Fluke, lied about her testimony and demonstrated a complete ignorance of how birth control works.