Still, as the Skout case showed, there are several recent trends that have heightened the concerns of child-safety experts: the rise of smartphones, which are harder for parents to monitor; location-oriented services, which are the darling of Net companies seeking more ad revenue from local businesses; and the rapid proliferation in phone and tablet apps, which don't always make clear what data they are using and distributing.
Filters and moderators are essential for a clean experience, said Claire Quinn, safety chief at a smaller site aimed at kids and young teens, Wee World.
But the programs and people cost money and can depress ad rates.
Things like too many 'unrequited' messages, or those that go unresponded to, also factor in, because they correlate with spamming or attempts to groom in quantity, as does analysis of the actual chats of convicted pedophiles.
Barring a wave of costly litigation or new laws, it is hard to see the protections getting much tougher, experts said.
Users could be unnerved about the extent to which their conversations are reviewed, at least by computer programs.'We've never wanted to set up an environment where we have employees looking at private communications, so it's really important that we use technology that has a very low false-positive rate,' he said.