You can also go through services like koshernet so things are prescreened and blocked. If you are on decent websites and things are inappropriately advertised there you should report it. I have seen photos on onlysimchas that should never have gotten through the screeners which I complained about and were removed. There are also posts on certain blogs that are reported and removed. WE each have a responsibility as decent people and good Jews to do our part to make the web and the world a decent place to be. So if I feel offended I speak up.
Recently I went on an auction site and lo and behold the first thing i saw was a Nazi swastika arm band for sale under collectibles. I immediately notified the PR department of the site that I was disgusted and offended that they allowed such revolting articles to be traded and sold on their website. I received a response immediately with an apology and a promise that they would have it removed and check into the seller, etc. We can’t just ignore what offends and disgusts us, if we are offended we have to say so. We need to do our own histadlus to stay away from the shmutz but if the shmutz follows us Speak up and shut it down.