This is another invented issue, designed to distract people from the real issues.
Truth: Politics is about self-interest, meaning they are there to represent their constituents. Whoever said that a senator from, say, Ohio is supposed to care about the people of Wyoming? He may, of course, but that's not what he was elected for.
What some people call "pork" (generally when speaking of projects in someone else's district), other people call "excellent constituent service". Like term limits, this is about people trying to deny OTHER people the benefits of government.
If the earmark is egregious, then let it be voted down. But who is to say what's egregious, besides the "bridge to nowhere"? McCain's ads refer to studies of bear DNA, supposedly to provoke people into derisive laughter. But who's to say what useful result may come from research on bear DNA? The whole point of science is that the investigation is what leads to discovery, NOT knowing where you're going before you begin.
I do get sick of all this fashionable cynicism.