Everyone is a potential client...or customer... aren't they?

Maybe it's the "networking" social sites I'm on- but i seem to attract a lot of people who seem to be  looking for more than Real Estate, and request to either be added to my "friends list" or "network" with me. 

At first I would decline almost anyone NOT in GA, anyone who has a graphic or X-rated profile...but then I got to thinking; could I be declining a potential client/customer?  :-(

So I'm having trouble knowing where to draw the line, by adding or denying those profiles who request to be on my 'friends list'- without losing business.  Any advice? How do you do it? 

 ~Nia