Here is the link to the examiner's report; http://www.fpsc.gov.pk/exams/css/examiner-report

An example of how I found this useful was in Islamiat remarks, the examiner has noted that the extraordinary papers had quotations from renowned and reputable books while the most recurring mistake they found was wrong Quranic arabic quotations. They specifically mention that the aspirants should try and better their arabic writing skills. So see one can get a fairly good picture of what the examiners want and then prepare accordingly.