klmno: Like you, I have limits set on my FB account - I've set privacy settings in multiple areas under profile info to "only friends."
StepTo2: I actually have "friends" from a variety of age groups; in general, people I know well in addition to some I hardly know, who live in my community; not so sure it was such a great idea to "expand" like that, lol. Anyway, I like being able to go on and see what's happening and only participate by making comments to friends here and there or an occasional private message to a friend of mine.
The posters in my above examples are young adults; maybe they are naive.
