Chinese Internet users face restrictions as to the websites that they can and cannot visit as China censors the Internet. It makes sense for Chinese companies to get an ICP number/license to ensure that its customers can easily visit its website without having to circumvent the ‘Great Firewall of China’.
When performing due diligence on Chinese stocks, I want to see that its website has an ICP number/license. Chinese websites will typically display the number at the very bottom of its webpages. Remember to check the Chinese version of a site as the English version may not show the ICP number.
Archive.org allows you to view past versions of a website.
EDIT (2/26/2014): On second thought, I don’t think that this is a good heuristic. For example, Mindray’s Chinese website doesn’t have an ICP number. However, I strongly believe that Mindray’s products are real. Other websites contain slick brochures for Mindray products. As well, Mindray has some pretty convincing Youtube videos.