I don’t think businesses should have the right to peep through personal facebook pages. It would be all the same if they got permission to come to your home and read your journals. Most people are able to keep their bad habits to themselves. Your personal thoughts and actions shouldn’t be an employer's business unless you start bring personal issues to work.
There was a time when a person’s personal life was separate from their professional life. A co-worker's personal life was just that, personal. People would come to work doing their job and go home. Some of my most phenomenal co-workers were people that I’d never hang out with as friends and that was cool. I learned a lot from them professional because they were great at their JOBS. Nowadays, I feel like employers who go through facebook pages are looking for friends at work and that’s counterproductive to me. This is how diversity in the workplace starts to slack off. First, you're making sure candidates are mellow non-smokers. The next thing you know, you're excluding people because of their political views or other affiliations. We have so much resegregation going on now, I'm starting to wonder how much of it started out with searching for "the right fit".
I wish they'd stick to doing regular background checks and leave the friendship searches for after hours.