It seems a lot like when schools jumped on the netnanny train. And then, one kid was trying to do a paper on Breast Cancer but all sites that mentioned "Breast" was blocked. No kind of filtering really works 100%.
So how can anyone block cp sites? If they do it with keywords in meta tags or even text on the page, they will take words that are used in everyday normal language. If they block something like pre-teen, there goes any family page or blog that talks about a Mother's problem with her pre-teen. The whole Lo lita thing drives me crazy. My sister in law is named Lo lita. She was named after her Mother's favorite book. Even we block the name
If they can find cp sites to block, why can't they find them and take the sites down?