In this instance, the company that went on the offensive was Cartier. Now, it is true that protecting your trademark, like protecting your copyright, is largely the responsibility of the owner of that intellectual property. When someone buys a Cartier watch, part of what they pay for is the Cartier name. Don't get me wrong, I'm not suggesting that police shouldn't try to catch dangerous sexual predators online. The primary reason is that people make stuff up when they're online.
People lie about who and what they are constantly.
Web sites, on the other hand, are a lot easier to evaluate when they involve the obvious stuff. Like counterfeit luxury goods. Think of something illegal, then go looking to see if you can find a Web site offering it. If the Web site is overseas, talk to the Customs service about it. Courts don't understand the Web.