Anyone who is overage and not an actual pedophile DOES know it's illegal - but that's not so much the problem as being lied to by an underage online partner. Your example is well-taken (and as I told someone else, I hope it didn't sound like I approve of overage/underage cybering - not my point at all).

Personally, I've stayed clear of cybering, and sticking to RP only for writing (with someone I know is well of age). And am glad of it ...