Even worse, sometimes people don't like to be told the truth. Paul Krugman wrote a magnificent hatchet job on a Michael Lind article a few years back taking him to task for not being able to add up, yet deigning to pontificate on trade theory as if he understood it.

Krugman made the very good point that a lot of people in positions of some power and influence who talk rubbish (which they often do on economics) don't like to be told that their "deep" thinking on world affairs rests on basic artithmetical or conceptual errors. And they may respond by shooting the messenger....