Defect of goods and poor quality of goods are two different things.
Comparation and contrast:
Defective products: the products having defects.有瑕疵的產品；不合格的產品。
Poor quality of products refer to the products are not certain to be defective, but poor in quality. 指的是產品不壹定有瑕疵或不合格，只不過是質量上稍微差了壹點而已。