The term "coffee" is usually employed in reference to the consumable beverage obtained by extracting roasted coffee with hot water, but it actually comprises a wide range of intermediate products, starting from the freshly harvested fruit (coffee cherries), then to green beans and to the final product of consumption (roasted coffee). Green coffee beans are the main item of international trade, and their quality is evaluated according to a wide variety of criteria, including bean size, color, and shape, processing method, crop year and flavor (cup quality). Among these, flavor is the most important criterion, and it is directly affected by the presence of the so-called defective coffee beans. The presence of defective beans is usually a consequence of problems that occur during harvesting and pre-processing operations. The most important defects are black, sour or brown, immature, bored or insect-damaged, and broken beans. Both black and sour defects are associated with bean fermentation and play a major role in downgrading coffee flavor. Immature beans (from immature fruits) contribute to beverage astringency. Such defective beans are usually present in the coffee produced in Brazil, due to the strippicking harvesting and processing practices adopted by the coffee producers. They are separated (color sorting) from the non-defective beans prior to commercialization in external markets, and the majority of these beans are dumped on the Brazilian internal market. Thus, the roasting industry in Brazil has been using these defective beans in blends with healthy ones, and, overall, a low-grade roasted coffee is consumed in the country. Currently there are no analytical methodologies that allow for detection and quantification of defective beans in roasted coffee, and thus an assessment of chemical attributes that could provide differentiation between defective and healthy coffee beans is of relevance. Thus, a review on physical and chemical attributes of defective coffee beans in comparison to healthy ones is herein provided, for both green and roasted coffees. Physical attributes include bean size, volume, density, color and water activity. Chemical attributes include proximate composition, acidity, pH, sucrose levels, caffeine, trigonelline, chlorogenic acids, amines and volatile substances. The evaluation of such attributes indicates that, in the case of green coffee, it is possible to differentiate defective and non-defective (healthy) beans by color, size, acidity levels, sucrose levels, and the presence of histamine. In the case of roasted coffee, only an evaluation of the volatile profile will effectively provide the means for differentiation.