When I noticed that the Guardian had run a feature on the top five embarrassing misprints, my first reaction (like many other people's, I'm sure) was to think about pots calling kettles black. However, it then transpired that they had included one of their own, on the paper's 1980 Christmas card - which then comes to seem like a warped kind of vanity.
Recently, though, the Guardian were the victims rather than the perpetrators of verbal vandalism, when a Washington Post tweet trumpeted the fact that they had "won the Pulitzer Prize for public service for our coverage of Snowden's NSA leaks, along with @GuradianUS". An innocent mistake or a calculated sleight of their accomplices?
(Thanks to Simon for the latter link.)