I had a link to the Fake Charities website in the sidebar for a long time, but recently it has appeared defunct. Now, according to the Devil, it's back up and running.
For the purposes of this exercise, a fake charity is one that receives more than £1m, or more than 10% of its income, from the Government. I have banged on enough about this in recent posts, so I will just say that a charity - by the definition of charity - gets its income from voluntary contributions. An organisation that is funded by money taken involuntarily from taxpayers and passed out by the government of the day to further its aims cannot be a charity in my book. The more that can be done to expose these arm's-length government agencies for what they are, the better.
The Devil explains the objection with greater lucidity here.