Since I care more about privacy than Mozilla does, I have the "Block reported attack sites" and "Block reported web forgeries" options turned off. Despite this, a blank 5-meg urlclassifier3.sqlite file keeps turning up and looking untidy in my profile directory. I'd be more annoyed if this directory hadn't become so opaque already after good old history.dat got moronically merged with the bookmarks, and the bookmarks backup format became randomly retarded and entirely inferior in Firefox 3, and the Cache folder got all fissured up a few versions after that, but anyway.

Trying to distill your comments down to an actionable bug. I suppose the real bug here is that you want urlclassifier3.sqlite to be deleted when the features which use it are disabled. I don't want to take anything you said out of context. Is that a correct assessment?

Yes.

Now that the storage backend has been rewritten, it no longer uses sqlite and all that's left to do is to clean up old profiles.