Anyone can be found, that is unless your pushing a shopping cart full of tin cans in an abandoned district of some city. Even then you can be found, as even bums / transients have historys. If you work, pay bills, bank, pay taxes, drive a car, use a computer, credit cards, or just breath, you can be found. Trust me.
The key is the many people who give clues to their identities in their posts. If you want to be anonymous, leave out identifying personal anecdotes, professional qualifications etc. Also, if you do, change your screen name often or use several.