There are three reasons it’s VASTLY better for most people to leave zero trail if they can at all help it:
1) It’s better to have some algorithm suspect you might be a hacker, than it is to open your mouth and remove all doubt.
Basic human psychology. If you’re not leaving a trail, you can’t make a mistake and leave too much of a trail.
Murphy on security: “If you can fuck up and compromise yourself, you will.” (I suspect lots of security types have first hand experience with this…)
2) Think mathematically. There are a thousand reasons you might decide to stop using Facialbook, but only one reason to “like” Rage Against the Machine.
Positive actions almost always carry more information than non-action. That one “like” encodes many, many bits of data — not just your preference, but the timestamp, IP address, the trail of clicks that got you there, who posted the item you liked, etc.
Each bit of data reflects something about you.
These systems quickly collect obscenely detailed personality profiles. Even if the profile you present is your “harmless side,” it can still be used to infer other details about you. How?
3) It’s NOT about “did he ‘like’ Snowden before he was cool?”
If someone wants to look at social networks and find who to watch, direct indicators are nearly useless. The kind of people who would Tweet the word “revolution” more than average, or who are friends with activists, are generally already known.
Instead, you take the profiles of everyone who was arrested at the last demonstration and use them to “train” an algorithm until it can — given otherwise innocuous data — predict that so-and-so is likely to cause trouble.
In this case, the relevant data may have nothing to do with overtly troublesome attributes. It may be people who have a habit of logging in at 3AM and who all listen to the same band that’s the deciding factor.
The fundamental problem is that every action you take still reflects “you,” and can therefore be used to derive information about you. The more unusual that action is, the more information about you it contains — even if it seems totally harmless to you!
If you’re really serious about staying off the radar, then sure, leaving a harmless data trail might help… but that requires either:
a) being able to compartmentalize your personality — creating multiple personalities in yourself, if you will — so your “social media side” knows nothing about the “real you,” or,
b) hiring someone boring as your social media manager to do the tweeting and liking on your behalf.