It is a legend that if you do not finish your bowl of rice that you will have bad skin. Little holes will develop in your skin from where the rice was made because food was wasted. Since wastefulness is an unattractive quality to the Chinese people, wasting their primary food will bring a physical unattractive quality. I find this traditional scolding a little annoying because when Chinese families all eat together there are usually courses after courses of food and so many plates to be eaten and much of the other food is not finished but the rice has to be. Rice is a very traditional dish but not the most delicious in my opinion.