Why would passengers' bad manners be dependent on the airline you fly? There are bad mannered passengers on every airline.
My suspicion is that on a non-stop oriented carrier such as CX, there might well be only two languages spoken by passengers (origin and destination) so the well-mannered but less than truthful ones will more likely ask due to the lack of language barriers. They might be more intimidated to try the same trick on a NW or UA NRT flight.