For those that don't know the Old Testament/Torah it might be worthwhile to point out that what you refer to as "moral failings" is not the same as what modern people think are "moral failings". Uncleanliness (gay sex, touching menstruating women, eating pork, yadda, yadda) and worshiping other Gods are "moral failings", raping, pillaging, and exterminating enemies most definitely are not.
Yes. The moral failing of Saul (1 Samuel 15) is precisely not following the command to exterminate Amalek, but rather sparing Agag, and taking spoils when he was commanded to kill everything that breathes.
