It's a tool...just like a chainsaw!
I use it to communicate with fellow photographers, sure I post a few "thought piece" posts but everything I post is purely related to photography and nothing else. I make a conscious decision to discuss technical ideas about composition and artistic interpretation. I've made contact with some great photographers, it's really helped me improve my photography and increase my circle of peers. That's where it ends though.
FB is a tool, potentially a very dangerous one. Treat it the same as you would a chainsaw or a powersaw, it's extremely useful but wear the right protection, consider every single move you make with it very carefully and only use it if you have to. Like a tool, if you don't treat it with the "respect" it deserves it will ruin your life in ways you cannot imagine.
Biting the hand that feeds IT
