The information I've encountered on this topic is a pile of employees and journalists on one side painting a grim picture of life as a FB mod, and this one throwaway account on HN implying it's not so bad. Forgive me if I find that hard to believe.
I've seen Goatse, though - maybe it's just that everything else pales in comparison.
What they see is: Penis. Pages and pages of penis. Penis in all shapes and sizes and orientations and conditions. But it was all penis.
Younger adults don't shock easily because (a) they typically have less and feel less responsibility, (b) the thrill of breaking the rules tempers natural disgust at seeing edgy material, and (c) they have less life experience to have learned empathy for some kinds of people.
Of course, I might be extrapolating foolishly from my own life. I used to have more stomach for cruelty.
Disgust is a cultural learning, not a natural response.
But if you have privacy expectation on fb...
I dont think that would hurt anyone then
Why would anyone use FB for that? It is already very hard to run legal sex related groups on FB. Registration is pain etc..
Some other social networks are full of porn, but even those have zero tolerance for this.
So I think the privacy expectation for that kind of thing is low.