What is the difference between saying "It's not good" and "It's no good"?
Native speaker’s answer
Rebecca
"No good" means something has no use or value and has no potential of becoming good. "Not good" means something is bad or undesirable. Since "no good" is being used as an adjective here, there is no difference between it and "not good". You could interchange the two and not affect the meaning of the sentence. Ex: This kettle is no good. The water is still cold. Ex: This kettle is not good. The water is still cold.