It really is unfair to compare McCain and Graham to muppets.
The muppet characters are lovable in their own way. There is nothing lovable about McCain or Graham. They are despicable jackasses. With his history of dumping his wife - who by all reports remained faithful during his years of captivity - for an heiress, his corruption evidenced by his Lincoln S&L escapades, and his utter disregard of the Constitution evidenced by his eponymous campaign finance reform act, McCain is particularly odious. He is kind of a Republican John F. Kerry. Of course no analogy is perfect: for example, there’s no evidence that Kerry ever sold his influence as openly and cheaply as McCain.
Occasionally they find themselves on the right side of an issue, but only by accident.
What’s really disappointing is Kelly Ayotte falling in with them the way she did.