Capn Nick, excellent points. We always have to remember that every Star Trek series shows things from the perspective of the Federation and its worldview. We should ask ourselves if Dukat is within the parameters of accepted Cardassian morality and ethical values, or whether he's violated the values of his own people. It's perhaps not helpful to judge him by human values, as he isn't human, nor was he raised on Earth or within the Federation. I'll hazard a guess and say that he was probably was, for the most part, until he went off the rails and became crazy. After all, I don't think he'd have gone as far as he did otherwise, as I'm thinking Cardassian society would have weeded out an individual that strayed too far from their values long before they could reach high rank.
I just re-watched Indiscretion and I think this is my favorite Dukat episode. He and Kira worked well together and they're able to laugh together, despite their history. And despite claiming to hate Dukat, it's obvious she feels comfortable with him and trusts him enough to be alone with him for over a week. And, as she said near the end, she knew Dukat wouldn't be able to kill Ziyal, because she recognized that he really loved Naprem and Ziyal. It's also obvious that Ziyal loved him, too. I have to admit I tear up every time I see that scene where he throws down the rifle and they embrace. And, at the end, Dukat is actually unselfish for once, taking Ziyal back to Cardassia with him, because she deserved a home and a father. *This* is the Dukat that I wish would have lasted until the end of the series. This is probably why the writers killed off Ziyal, as a prelude to totally ruining the character of Dukat.