Well you know most internet tough guys are lying simply because they would be in jail as opposed to on the geek-forum of choice if they were even half serious.
Also people who think being a sociopath is cool are totally insane, albeit in a differant way.
See, I've spent a reasonable portion of my life (especially childhood) institutionalized as I've mentioned before. I "recovered" somewhat, worked for 10 years, and then started having issues again and wound up retiring on disabillity.
My emotional problems probably stem from damage to my head when I was a baby, causing probably brain damage (the soft spot on my head didn't close up properly and had to be wedged open with a plate for a while, to this day I have a soup-bowl like dent on the top of my skull with a huge scar in it).
Right now I an considered "undiagnosed" because they probably stem from physical damage and can be erratic, but over the years I've been Manic, Bi-Polar, and Borderline Personality (some wanted to keep me locked up for my entire life, especially when I was younger for reasons I won't go into).
Let me be brutally honest with you, I can empathize with some of what Dexter is like, but then again everyone can, which is why the show is so successful. *BUT* Dexter doesn't quite have it right in what being a sociopath is. Dexter is emotionally repressed, that's part of the entire show. He has emotions, he just doesn't like to admit them.
Being a sociopath means being totally self centered and being unable to form connections with other people unless it benefits you in an immediate sense. If you can fake it like a certain TV character or do the same things he does then your not really a true sociopath or borderline personality.
I have some understanding of it because I have done some research on the stuff I've been diagnosed with (or suspected of). It helps me deal with my problems and understand the conclusions some reached (or thought they reached).
The "stone killer with ice water in his veins" has always been "cool" and has been a stereotype for both a hero and villain for almost forever, but in most cases such characters are simply heavily in control of themselves (to an unreal degree) not "sociopaths".
Also for the record with some of the hot, blind rages I've had over the years, combined with some other (fairly cool) outbursts, I can say for a fact that such problems are not "fun" or "cool". Nor is it the kind of thing your going to be able to talk about in some kind of "oh I am so awesome and tortured, feel my angst" fashion. Instead any REAL discussion of it is going to come accross like your in a bloody therepy session.
Writers who create sociopaths and such generally work from textbooks and interviews. Only a real sociopath could write a sociopath. Me, I'm not a full-on sociopath, but I definatly have the tendencies as much as I try and work on them.
... and honestly, if your truely as far gone as many people try and claim on the internet (as part of this fad which I also recognize), I'll be honest: nobody is going to teach you to be truely dangerous. That's just fantasy because it sounds cool. Your real sociopath gets to bounce around in a cage, or co-star in the video below:
http://www.youtube.com/watch?v=uF5M-h2IueU