In theory, we would have a perfect ratings system that would keep children from ever seeing anything they are not "supposed" to see. But, that's the problem. We know that they will see things that are inappropriate, and handing those incidents becomes an opportunity to be a parent. You must explain and answer questions when a child is exposed to something. It might be a pain in the ass to talk to your kid, but oh well. You birthed it, you own it, in other words. And no ratings system is ever going to be enough.
The kids already know what's going on. They're going to find a way around a ratings system and they're going to watch and listen to things that are dangerous and exciting. You have to regulate that as best you can but you also have to understand that they are just like you were, and you were a little deviant and daring back in the day, too.
It's sad to see Annie Lennox complaining about sexy, disturbing and dark videos when she has a library full of them that people still watch.
We are all Annie Lennox/Dave Stewart/Eurythmics around here, and the funny thing is, I was never a fan. Ever.