And the thing is that not only does everyone think that they're Good and everyone else is Evil, they also have a reasonable point, from their own perspectives - anyone can be the Bad Guy if you try hard enough. Stanley is an egotistical idiot. The royals are elitist snobs. The big sides are bullies. The little sides are wimps. The powerful sides are thugs. The clever sides are untrustworthy. On the other hand, nobody that we've seen goes out of their way to be needlessly cruel or underhanded, with the sole exception of Olive Branch. From their own perspective, each side is trying to take out the "Bad Guy" while improving things for the people on their Side. Even if they're not good, they're trying to be.
...except, of course, for Charlie. The one who remains absolutely neutral at all times, who'll be reasonable or ruthless on a whim, who anybody can rely upon if they have the schmuckers, but who nobody actually trusts. Charlie is the only Ruler we've seen who completely disregards morality.
And if you think about it, if Charlie is the only unit in Erfworld who's not at least trying to be any version of "Good", then that also makes him the closest thing we have to "Evil". Or at least, so utterly amoral that he might as well be.
Although, operating under the " best to the side=good" version of morality, Charlie is no less "good" than any other side, sometimes even more so, I'd think. Incidentally, under that model, I don't think any successful side could be "evil", so it's probably flawed...