First, I am not in the cult of Palin, so yeah, if she made 3rd party threats I'd call her sleazy as well. As it happens though, she made crystal clear when she made her announcement declining to run on Mark Levin's show that she was under no circumstances going to run 3rd party.
The reason Paul is a sleaze is because he is just using the Republican label for his own ends. He is a libertarian, NOT a conservative. He is using the Republican label ONLY because he couldn't win an election to dog catcher with the Libertarian label that actually better suits him.
Hannity and Rush pretty much say the same thing. The constantly say that the just regard the GOP as a vehicle to advance an ideology not as an end in itself. The Libertarian label suits him? Apparently the voters in his district who elected him overwhelming in each election disagree with you. Aren't they the best judge?