That's what destroying the videotaped "interrogations" of Al-Qaeda members amounted to, if you accept at face value the Bush Administration claim that the interrogation methods were ethical and produced valuable information. The tapes were perfect training materials - actual "interrogators" getting actual information from actually resisting enemies. To say they were destroyed to protect interrogator identities is ridiculous - the interrogators' faces and voices could have been easily obscured.
So either it was criminally incompetent to destroy something so valuable if the Bush/Republican approach is justified, or it was criminal obstruction of justice to destroy evidence of governmental interrogators committing crimes authorized high up the chain of command.
Kevin Drum has more on the uselessness of these particular results.