That's the thing, it's not a good v. bad situation. It's supposed to be as close to a "real" world as possible. Everybody thinks of themselves as the good guy. If you're Cersei Lannister, all of your actions are justified. Renly, Stannis, Rob Stark, they are the bad guys from her perspective. I don't think the show accomplishes this very well, because it doesn't make for great tv. TV watchers don't want to think. They want a knight in shining armor to vanquish a terrible scourge and woo a pretty lady.