After blogging for nearly two years, I find that there are plenty of people out there that don’t have the slightest clue what commentators can do to a post, left unchecked. Much more than that, what they can do to your site overall without some amount of auditing by the site author.
Keyword hijacking in the classic sense is where a blogger creates a post that is outside of their niche in an attempt to drive traffic to a page by means of popular keywords.
Doesn’t sound to bad so far, right? Just read on, take this example for instance:

The missed opportunity many blog commenters forget about, 3 way links
April 18, 2011 Link BuildingLeaving comments on blog posts and articles is a wonderful thing, don’t ya think? I mean, never in our life have we been given such a microphone to broadcast our thoughts about anything we want, to so many. I assume you’re not a news anchorman, by the way. It’s an awesome power to have. We [...]