This is an interesting question! I think there are actually several different expressions here and unfortunately you will have to memorize all of them. 1. "be good FOR" + noun = it is healthy, it improves you, it has a positive effect on someone or something Vitamins are good for me. (Kimchi's sentence) Fried chicken is delicious but it isn't good for you. A few days on the beach will be good for Tom. Drink this tea. It's good for colds. (= the tea will cure your cold) 2. "be good TO" + person = behave nicely with someone, treat someone well Be good to your little brother while your father and I are out tonight. I don't want to change jobs. This company has always been good to me. 3. "to me" -- a totally different expression that means "in my opinion." It is often used to compare your opinion with other people's opinions. To me, Christmas is about spending time with family. Some people hate peanut butter, but to me, it's delicious. People call it "stinky tofu" but it smells good to me. That sounds like a good idea to me. "Is it good for me?" means "Is this healthy?" or "Will it help me?" "Is it good to me?" is probably wrong. Maybe you could ask that if you are not sure if a robot will treat you well. But people often ask questions like, "Is your boyfriend good to you?" or "Is she good to him?" You also asked kimchi about this sentence: "The food might have tasted bad TO HER, but it is good TO ME." Both of the prepositions should be TO since they have the meaning of expression #3 above. I hope this helps!

"For" = in support of or in favor of, for example: Vitamins are good for me. Exercising is good for me. Clean water is good for me. "To" = shows that it is being directed towards you, for example: It is good to me The teacher was good to me. The big dog was good to me. The food might have tasted bad for her, but it is good to me. The movie seemed good to me.

Those words ("to" and "for") are among the small common words of English and a picture of every meaning is in the book "keys to words" which you can find at: http://www.keys2words.info/ The answer to your question and all your questions about the 60 small common words are answered in the book which is guaranteed to improve any student's English. My Skype: brian.madden4

A classic question and why I wrote "keys to words"