I remember talking to an FOI when they had an office at Moorabbin many years ago. In those days recurrent training by FOI's was allowed. This FOI discovered that when he rang a flying school to book an aircraft for his own personal practice, he would be told no aircraft were available. He discovered it was because he had a reputation for recording defects in the maintenance release which upset the aircraft owners. Problem fixed - don't hire aircraft out to FOI's. Nothing couldn't be proven and the flying school operator knew this