In my mind the Oath should be strict but comply with the ethos of thier god. You are playing a character in a world where thier is no doubt the god is alive and that he has given you the word. I always judge the paladin by the god or goddess they worship. a god who espoused mercy or forgiveness will probably be more forgiving than a god who is all about harshly hunting down and destroying evil. Minor failings might be dealt with by local church leaders and ignored by the diety. Antipaladins are fun, most evil dieties are unforgiving and might even punish them for simply failing even though they did everything by their code. And leaving them is almost never a survivable option.