Although double negatives, which consist of two negative words in the same sentence, are sometimes used in informal speech as well as in songs lyrics, they are not encouraged in the English language because they not only reflect poor grammar but also they can be confusing.
Bearing the above in mind, it could be said that in the sentence <em>"The picture isn’t no good"</em>, the vague or unacceptable word is <u>no.</u>
