Warning, this is a bad site!
My answer to Warning, this is a bad site! on Ask MetaFilter
Unfortunately it’s not a glitch in the matrix—this happened to a friend of mine. If a site gets this warning and isn’t listed on StopBadWare.org it just means that Google have blacklisted it themselves—they don’t share their reasons with StopBadWare, and provide no mechanism to find out why they’ve blacklisted you. The link to StopBadWare is something of a red herring.
Unfortunately there’s nothing I can suggest as a remedy—Google are completely uncommunicative about this issue, which I think is scandalous.
Then at 12:43:
The wiki could be the problem—he really needs to scan through absolutely every page / link on the site looking for anything nasty. My friend’s site was eventually re-included.