DEAR ABBY: I was surprised at your answer to "Mr. Clean Plate," who asked if it was considered bad manners to eat everything on the plate. You said, "It's bad manners to mop up every drop of gravy with a piece of bread, but to deliberately leave edible food on one's plate for the sake of `appearances' is both wasteful and foolish."

Abby, my grandmother (a very gracious lady) taught me that to leave a bit of food on my plate is a compliment to the hostess - implying that the meal was delicious, the amount served was adequate, and the guest could not possibly have eaten another bite."We must remember," she would say, "never to eat the tip end of a banana, or the bottom tip of an ice cream cone. Nor should one drink the last swallow from a glass or cup." - REMEMBERING GRANNY IN CORONADO, CALIF.

DEAR REMEMBERING: Obviously your grandmother and mine went to different schools. My grandmother (and my mother, too) would remind us of the "starving Armenians" if we wasted food.

I agree, it's bad manners to voraciously devour every edible morsel, but to throw away the tip of an ice cream cone for appearance's sake is a ridiculous affectation.

DEAR ABBY: I commend you for addressing the topic of genital herpes in your column. However, you recently provided some advice that is incorrect and potentially dangerous. You stated that "if there are no symptoms, sores or active lesions, your partner is not infectious." This is clearly NOT true, and heeding this advice could result in couples disregarding precautions necessary to avoid transmission of genital herpes to the uninfected partner.

While asymptomatic intervals carry a decreased risk of transmission, infected persons are still capable of transmitting the virus.

When symptoms or sores are pres-ent, sexual contact with the involved area should be avoided completely. Because of the risk of asymptomatic transmission, condoms should be used with each sexual act. Bluntly put: There is always SOME risk, although condoms will serve to decrease this risk. - WILLARD CATES JR., M.D., M.P.H., DIRECTOR, DIVISION OF SEXUALLY TRANSMITTED DISEASES, CENTERS FOR DISEASE CONTROL

DEAR DR. CATES: Thank you for your timely and enlightening article. The professional medical experts who advised me on this issue obviously had a different opinion. I'm sure I'll hear from other experts on this topic. Readers: Stay tuned.