Using SharePoint 2010 (no idea how this affects 2007 or 2013), I often use Personal Views for administrative purposes, partly for "security through obscurity," mostly to keep the UI uncluttered for my end-users. I use SharePoint Designer to apply custom CAML when the need arises, but Designer does not seem to be able to see Personal Views in a way that allows me to edit the CAML of particular Personal Views.
Personal Views don't show up in the usual Views Report for Lists/Libraries, and navigating via All Files to PersonalViews.aspx yields only the base Personal View page. (I can't see a way to load in the customized contents for a given personal view; you just get the template.)
My workaround has always been to create a public view, apply my custom CAML, complete the administrative task, and delete the view. Is there a better way?