Yes, the comment systems of major blogs such as Engadget and TechCrunch are filled with filth. (disclosure: I gained my fame/infamy through the TechCrunch comments section). That's when the GIFT and Law of Large Numbers meet, and it isn't pretty.
But high quality content yields high quality content. Articles that are insightful, like analyses that hit the top of HN, don't attract stupidity. Playing curation games with your comments (such as Gawker's "we hide all your comments unless we like you.") alienate your users, and it is somewhat selfish from the author's perspective.
A good compromise is Facebook Comments, which discourages trolls who aren't willing to be anonymous. It doesn't eliminate them, but it's a very strong start, and easy to implement.