I, am neither "naive" nor "incredibly cunning" in a dangerous way.
My real name doesn't appear anywhere online (not from my activity anyway- others may talk about me)- and I haven't signed up for any social networks- although I am very active on forums and blogs like this one.
As a kid on the old BBSs that were popular before the internet got big, my brother used to watch the forums for things I said that he could report to my parents to get me in trouble. Even though I used an alias- he knew what my alias was. I got in trouble too many times for things I posted online not to be carefull.
As a result- I learnt very early on to hide my real name (and even my alias where possible) from anyone who might want to track me for nefarious purposes. Now, I never use the same name on more than one place I comment.