If you read up on how he was caught, it was pretty incredible - another journalist at Der Spiegel had to go on a personal mission, on his own time and at his own cost, to prove the guy was lying, and then nearly lost his job because the management couldn't accept it. The fact checking department had been hoodwinked for years despite some truly dubious and insane things that had appeared in his stories.

Yes, he got caught in the end. But he shouldn't have been able to publish such obvious nonsense for years on end. It's quite clear that Der Spiegel didn't catch him because he was telling them what they wanted to hear.