RLS--
The "sneaky" games you describe are all too familiar! I feel as though we are constantly playing spy vs spy....
The bottom line for us, though, is that difficult child simply cannot be trusted. We monitor phone calls and email and computer usage and STILL recognize that she is probably using other kids' computers and cell phones to send messages that she doesn't want us to see. It's all so ridiculous because all we really want is to protect her from herself--and she is so determined to engage in dangerous and inappropriate activites.
If they are really determined to "get around" their parents--there are 1000 ways to do it.
I wish I had the answer. I'd share it with you in a heartbeat!
--DaisyFace