I have a lot of parents/teachers at the school where I work friend me and we never talk on FB but I can't unfriend them exactly....well I can now that I am not working there. I guess, but still...it was weird when I did work there
Here is what I did....
I have divided my friends into lists (it is under the "friends" tab.)
I have different lists and basically only my friends I know can see my stuff, status and pictures.
I created a list in the friends tab called "no shows" and then have customized my settings so they can not see anything.
My half little brother is on there and it is "cool" to have lots of friends and a lot of his friends I have never met have friended me just to have the number. I think that is what some people do.
But be safe the internet is scary.
If anyone has questions about how to do this please PM or ask me. I have set up privacy settings for a lot of the teachers at school and am happy to help if you need it.