Currently several wikis use $wgGroupPermissions['*']['read']=false to mimic a private wiki. This is a really really bad thing as while people see it as private, we do not. As such it gets added to monitoring lists, we'd eventually start publishing statistics and other information public which shouldn't be public.
Wikis need to be a) public or b) private (as in wmgPrivateWikis) otherwise we're running into a hole of publishing information for private wikis.
The following wikis fall into this category: