I like to think I have a good enough ear for the language to recognize whether a post is coming from an "intelligence source" on one side or another or truly from someone who is what they say they are, frontline grunt or Baghdad citizen. When I was playing Majestic[*], for example, I had very little trouble telling the 'real' sites from the ones developed purely for the game - you ended up visiting both in the course of play. One of the other players developed a little script that would go query and find out who ultimately owned the domain, so you could plug the url you were curious about into the applet and find out which sites were purely game-created, and which weren't. Like Neil Gaiman mentions in his blog, you'd be amazed at some of the wackiness out there - you can't make this stuff up.
*The game came out mid-2001, and was somewhat abruptly dropped after September 11 that year, when it suddenly became far less popular to speculate about government conspiracy and intrigue.