Just need to add my 2 pennies worth:
In my experience, which has dealt with crews from all over the planet, the vast majority is a nice bunch who only ask operationally well-funded questions. However, every now and then a hard head will waltz into your office, confident that he is the closet thing to God than man has seen for 2000 years. There is no way a mere mortal will ever convince him that anything he says, does, eats or breathes is anything but perfect, and that he ('cause it is NEVER a she) has every right to command your full attention to his every problem or concern. There is but one way to deal with these people: Professionally, cool, detached ! And when the (explicit) has vacated terra firma, make sure to write a nastygram to his chief pilot explaining how he corrupted your operation. Mind you, whilst the aircraft is on the ground, the flight deck crew must remain seated in their crew lounge, preparing whatever they need to and leave you alone to mind YOUR end of the business.
Smokin'