An Embarrassment is Coming
If they don't invest the time in reviewing the information that's been published about them, Facebook users are in for a potentially embarrassing surprise. That's because Facebook is working toward making more of its content searchable with its Graphs Search feature.
What will be searchable? All the information (personal, professional, pictorial) you post, and that other Facebook users post about you. Additionally, your likes, and in many cases simply the websites you've visited that have hooks back into Facebook, will be searchable.
This article explains it well, and in it, writer Meghan Kelly gives one of the best analogies for Facebook I have read:
Facebook is like a safe containing a ton of your personal information - which you've purposefully and willfully cracked with an axe.
Beyond searching for what's already out there about you, commit to practicing good social etiquette. Don't "check in" your friends for them (without their knowledge!), post pictures of them they may not appreciate or tag them to one of your posts without their permission. Even the tamest of details may cause trouble for them, not to mention, trouble for your relationship.