Represents the pleasantness or unpleasantness of an odour. It is subjective to each person and therefore may evoke an emotional response depending on experiences with that odour. It measures how acceptable an odour may be and is indicative of the potential of an odour becoming a complaint. Some form of scale is used to judge the odour. According to VDI3882, a scale of -4 to 4 is used. -4 represents extremely unpleasant odour, 0 represents neutral odour and 4 represents extremely pleasant odour.