Don't make the mistake of engagement. At some point at every company I've worked for, we got lazy during the "cultural fit" part of the interviews and at least one of these guys slipped through and got hired. We usually eventually let them do something like maintain the build server or ticket tracker. That usually kept them from doing harmful stuff like alphabetizing the method names in classes or reformatting all the source code for "proper indentation". The key though, is to never engage them in a conversation. Let them go home to their silent, empty apartment and pull wings off of beetles, or whatever their true dark passion is. But don't engage. You're just better off not knowing how far certain peculiarities go...
