A report from ScanSafe claims 80 percent of all blogs contain "offensive" and potentially "unwanted" content:
ScanSafe's Monthly "Global Threat Report" for March 2007 says that up to 80 percent of blogs host offensive content, ranging from "adult language" to pornographic images. The company suggests that businesses should be aggressive about preventing users from accessing some or all of this material. And of course, they'd hope that you'd use their products to do so.
ScanSafe says that it discovered the "offensive" nature of blogs by analyzing more than 7 billion web requests coming from their corporate customers. In doing so, they apparently learned that the so-called blogosphere is a lot like a George Carlin performance: diverse, sometimes entertaining, and loaded with "bad words."
The firm also found about six percent of all blogs are loaded with some sort of malware. More info at ARS Technica.