To address the first post; the practice is definitely not OK, except maybe in one circumstance. If the examiner, in his brief, informed the candidate that during the flight he may issue some instructions that would contravene the rules of the air and should not be complied with, then possibly it might be acceptable (but I would suggest almost certainly unnecessary). Otherwise nyet tovarich.
From the UK Flight Examiner's Handbook, section 4.1.2: 'They [examiners] should not set any traps or pitfalls'.