You know, it's funny. I -have- come across sites like that, before.
One instance for example, was a few years back when I was trying to go to gamefaqs to look up some cheats for whatever game I was playing. By accident, I left out the s at the end, and it sent me to a rather explicit, gay porn website.
So, to those who say it doesn't happen, be glad you haven't had that happen, or that it hasn't happened to your kids. Because it damn well does happen.