Limbaugh has proven to be more teflon/bulletproof than Bill Clinton. O'Reilly the same.
The degree of success of larger-than-life personalities like Limbaugh, O'Reilly, and Coulter is directly proportional to how much they annoy the left, but the left never gets that. They are under the mistaken impression that extreme outrage will kill these pundits, but that outrage only makes them more attractive to their base -- drug addictions, lies, respectively, and voter fraud notwithstanding.
(EDIT: the word "respectively" was added to make it clear who I was accusing of being a drug addict, liar, and fraud.)