Surely there are professional social networking sites geared toward academia (if not, please let me know – that’s a business opportunity waiting to happen).
Doing your professional networking on Facebook is like choosing to hold an academic conference in a derelict Chuck-E-Cheese that’s filled with rat poop and that has deranged old people shouting racist statements wandering through it, while creepy voyeurs record the attendees’ every move and sell the footage to fascists and grifters.