Well this is trickish, however I do believe that leaving remnant of food on a plate or eating everything on a plate in a restaurant makes one either starved or classy.
It all depends on mentality, you see some men rich men in a restaurant hardly finishes their meal it's not because they feel classy but because they hardly even eat too much, meanwhile others finish their meals in a restaurant and get done with it, it's a matter of mentality and doesn't have to do with either being rich or being poor or being classy or being mundane.
Food in a restaurant is purchased with hard earned money and finishing the meal or leaving part of it signifies nothing