I'm generally quite paranoid about internet security, but even I am not worried about this. I highly doubt that there is someone whose actual job it is to sit at a computer all day long and wade through the crap posted on this forum and others like it. If there is, then I pity them. It's more likely to be done by some sort of computer programme that looks for key words or phrases being mentioned. And if it is reviewed by a human being, anyone with an ounce of common sense could usually tell the difference between weirdos and losers acting out their fantasy lives, and those who pose an actual danger.
At the end of the day, nothing on the internet is private. I use TOR and a VPN, hushmail email accounts and I'm not on facebook or anything, yet even so I wouldn't assume I'm untraceable. And I'd be willing to stand by every word I've said online, because I wouldn't be so naive as to talk about actual criminal stuff here. Not that I've ever done anything remotely criminal, of course...
by Daddy
But don't forget that depending on the severity and country relations... extradition is possible.
Terrifying though tk's attempts at erotic fiction writing are, I'd be willing to bet the good folks of the CIA have bigger badasses to worry about. I think we're fairly safe here.