Some great comments here, It must be remembered that an examiner is just that!, examining. What he is examining is the candidates ability to meet the respective standards set forth by the aviation body of the respecive country. He is not an Instructor and cannot be during the check, now, in the US an examiner can ask a candidate to redo a manoever if he deems it unsat (part 135) but still has to make a judgement call if it is unsat again.
What must be remembered is that examiners were instructors in a former life and do understand what is going on, when I see a candidate make a mistake it reminds me of my instructor days and I have to ask myself if this was a mistake or a lack of knowledge and understanding of the task at hand. This often forms my opinion during the debrief regardless of the outcome.