I'm always wary of unsolicited private messages, epsically ones with links in the,. Thanks for the warning.
I don't know how they target people because I don't receive any of these.
And what do they say? "You just won 1000 btc, click here to receive them"?
![Cheesy](https://bitcointalk.org/Smileys/default/cheesy.gif)
I think it's usually something like "you just won x btc, download the private key: wallet.dat.exe"