How to identify parody on the internet?

I ran across this article on the "Scoop Independent News" website while searching for Casey's gravesite location. After reading it became fairly obvious it is a parody, however for much of the world, particularly the Middle East, they may not be able to tell that. After I thought about it for awhile I realized that a lot of people in the U.S. that either don't pay attention to the news or just certain sites may also not get that this article is not and could not be true.

So I did a search for "riding across the symbolic gravesite of Casey Sheehan" on Google and found 22 postings. This same story was repeated on www.SQLSpace.com "No Censorship Zone", the Inbox Robot - A News Service for Research Professionals, blondesense.blogspot.com, www.gregpalast.com (the story's author), www.freepress.org, www.opednews.com,sf.indymedia.org, www.maavak.net, www.apfn.net/messageboard, peaceandjustice.org, carapace.weblogs.us (Not Your Father's America), illuminati-news.com, www.legitgov.org, and a commetator on www.astroworld.us. Not a single site reported this as a parody and in fact most sites were made to look like real news sites. So exactly how many people are being fooled by such "reporting" on these sites?