I can understand that. If you catch a child watching abusive porm or something that's just flat out disgusting on every level then yes, you have full reason to be pissed at them. Problem is though that they'll just take it with a grain of salt and get what they want from their friends. (No not six, images of whatever it was they watched or the use of their internet just to look it up.)
Edit: But again, just sit down with them and talk them. Explain what they saw. Explain why you're pissed. Explain whatever it is you need to explain. Don't just blow up on them and think it's all done with and little angle will never peek at devil film again.
I agree, that's the difficult part of online porm. Even the most mainstream pormsites, at least the free ones, are basically just a dump for all kinds of pormography, with no separation between normal porm and the worst fetishes. However, whenever I look up porm, and I see something truly [censored] up, I don't watch it, I move on and try to forget what I saw. I realize it's harder for a younger kid to do that, especially one that's not spending a lot of time online and is to a certain degree used to seing the worst parts of it.
So let me repeat what I said. There is nothing wrong with the concept of pormography itself. But there is a lot of stuff out there that just shouldn't be watched by anyone. However, if I had a kid, and I caught him watching porm. Instead of being angry and condemning it, I'd talk to him/her and explain just how saturated the internet is with crap that you really do not want to see. And rather than trying to ban them from watching porm in general, I'd rather just tell them to be carefull and be aware of the fact that you can stumble across all kinds of weird crap online.
Call me what you want, but I will
never become a puritan who condemns something without a sensible reason behind it. I condemn child porm, however that doesn't mean all porm deserves the same treatment.