No good is colloquially used as both noun and adjective to mean "without worth," "of no use or value," "good-for-nothing," "useless": "This tramp is a no good." "This steak is no good." Worthless is more acceptable in the meanings cited above: "This counterfeit money is worthless." No good is an acceptable term in a statement such as "Your help did me no good," in which good is a noun, not an adjective.
Dictionary of problem words and expressions. Harry Shaw. 1975.