No "bloody nose" for the Tories or Lib Dems?

When the MPs expenses scandal erupted, I fully expected all three "major parties" in British politics (Labour, Conservative and Liberal-Democrat) to get punished at the polling booths. No such luck. The recent Local & Euro elections delivered a "bloody nose" to the governing Labour Party, but left the noses of the equally corrupt opposition intact. I have one question for the British voting public: WTF?