Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Distinguish between good and well, bad and badly
Choose adjectives and adverbs with care
Grammar

Good is an adjective (good performance). Well is an adverb when it modifies a verb (speak well). The use of the adjective good in place of the adverb well to modify a verb is nonstandard, even though it is common in casual speech.

Confusion can arise because well is an adjective when it modifies a noun or pronoun and means “healthy” or “satisfactory” (The babies were well and warm).

Bad is always an adjective and should be used to modify a noun; badly is always an adverb and should be used to modify a verb. The adverb badly is often used inappropriately to describe a noun, especially following a linking verb.