It probably depends on what you use FB for. I primarily use it to keep in touch with relatives, so I don't use it as a general blog or anything, and I do censor what I say. (Honestly, I think everyone should do that anyway, but that's another subject.)<br><br>
But FBing with an unstable person can be...very stressful. I've recently had to lock down my wall since my mom is going through a psycho stage right now (and I'm always the target of her rages). She left a very embarassing and inappropriate wall post (luckily I saw it within seconds as I happened to be online, so I removed it before anyone else saw it probably). And she has been using FB mail for nastygrams. I am very close to just "hiding" her, but she seems to be calming down since it seems like I'm totally ignoring her and not engaging. I really didn't want to friend her, but again, it's become a family way to keep in touch, I already heavily self-edit, and sadly now I know it's something that she probably will attempt to use in the future to embarass or manipulate me (unsuccesfully, since invariably she always shocks people and makes herself look...well, like a crazy person).<br><br>
I'm not sure what you mean about "unstable" though. I think you should only FB someone if they fit in clearly to your FB mindframe (as Sierra mentioned--some people use it only for friends or work contacts or family or whatever), and in the case of someone that you don't know well or have reservations about you need to be willing to monitor their activities on your portion. You also need to be able to handle whatever TMI they put on their own page (that you will be able to see unless you hide them). Some people couldn't care less about TMI (me) others really get worked up over other people's life decisions, ect.