Casey Johnston writing for Ars Technica:

One study referred to this process as “social investigation.” We developed particular behaviors to avoid creating suspicion: do not “like” anything by the object of a stalking session, or if we do like it, don’t “like” too quickly; be careful not to type a name we want to search into the status field by accident; set an object of monitoring as a “close friend,” even if they aren’t, so their updates show up without fail; friend their friends; surreptitiously visit profile pages multiple times a day in case we missed anything.

This passive monitoring is one of the more utilitarian uses of Facebook. It’s also one of the most addictive. […] Facebook did away with the necessity of keeping tabs on anyone. You simply had all of the tabs, all of the time, with the most recent information whenever you wanted to look at them.

And

The novelty of Facebook was bound to wear off. For my part, I rarely post on friends’ walls except to wish them happy birthday; I stay the heck away from saying anything substantive in comments on other people’s posts; I don’t post anything myself.

One of the reasons I try to avoid Facebook. People tend to read too much into simple likes and friend connections. It gets worse when one naively attempts to connect the dots of online activity to real life.

Sure, Facebook provides privacy controls but they are a moving target. Also who wants spend time managing that? I prefer the Twitter approach. Either everything is public or not.