I've been pondering on this myself in recent weeks.

GH Bangkok awards points on the 10% service charge on room rates but GH Tokyo doesn't.

Today I've had interesting discoveries at the Bakery at GH Bangkok. Keen to top up my points to achieve a certain threshold, some items of pastry award points whereas others do not. And at times the eligible spend is zero when charged to the room, whereas the full bill earns full points when it is paid there and then as part of "hotel dining". Very confusing.