Gul Dukak = coolest villain on Star Trek.
But really though. I never thought he was pure evil until probably the very end... Then I thought, "There's no hope for him. He actually is pure evil." But by then he was dead.
I seem to have come to this conclusion about a year (in Star Trek time) later than most of the characters.
In "Waltz" Sisko at the end says that he now realizes that Dukat is pure evil. (At least I think he said that. It's been so long.) And then of course there's Kira who probably realized this during the occupation.
But for the most part, I always though Dukat could go either way. And I even when looked at him in situations when he was supposed to be portrayed as this big evil powerful Cardassian, I could usually still see from his point of view and understand that he might not have thought what he was doing was all that evil.