I recently played with someone who played a traditional paladin -- roamed around questing to help people, prayed to his god every morning, proselytized to everyone who would listen. But we were playing in a setting that was hostile to adventurers because they have historically entered the area simply to loot it and destroyed the ecosystem on the way. The paladin constantly refused to understand this perspective and happily talked about taking loot and killing local fauna right in front of my character, the local guide who had reluctantly agreed to help the party despite said hostility towards adventurers.
Was the paladin acting according to his oath? Sure, he was doing what his god told him to do. Was the paladin objectively good? I actually find that debatable, and I would have had objections if the DM had chosen to validate his supposed goodness by presenting him with some magical item that is supposed to measure inherent goodness.