As you notice in GoT, the people you have a tendency to want to live, die. And those you'd wish dead, tend to live longer than you'd like. (Like Joffrey) Martin has found an excellent way to take characters that aren't necessarily good, though, and build up an affection for them from the audience. Take someone like Theon - He's an absolutely unbearable ass, until he gets his tortured to no end - Then the audience begins to side with him. Or Tyrion - my understanding of Tyrion is that he's almost a universally loved character - Perhaps more because of how well Dinklage plays him, but regardless - Tyrion is still a Lannister that's committed horrible deeds in the family name. Or Jaime for that matter - yet both Jaime and Tyrion become extremely likeable as the show goes on.
Or Littlefinger - I really enjoy Littlefinger as a character, and his misdeeds don't really bother me.