As a GM the urge is to overlook failure, just nod at the bad roll and move along to spare the player the shame. Big mistake. The worst insult to a character in the game world is to have no impact.
He goes on to talk about describing failure as the result of bad luck or other unfortunate circumstances, and not just a screw-up on the part of the PC — much like Jonathon Tweet’s Kirk Rule (Captain Kirk never fails!).
Good stuff all around — every GM should consider this often-overlooked topic.