The study aimed to map different ethical positions regarding the way in which 107 adolescent athletes (Mage = 13.64, SD = 1.64) and 157 adults including 44 non-athletes (Mage = 20.56, SD = 2.98), 94 amateur athletes (Mage = 20.61, SD = 2.77), and 19 professional athletes (Mage = 20.52, SD = 2.52) used different informational cues (the consequences for health, the level of detectability, the short-term outcome, and the Coach’s attitude (CA)) for judging how acceptable it is to use a nutritional supplement in sport. The participants indicated their judgment of acceptability in 36 scenarios constructed from the combination of these information cues. Cluster analyses, ANOVAs, and chi-square tests were done. From the total number of participants, two different ethical positions were found according to the age. The adolescents (61%) judged that using a nutritional supplement is acceptable when the negative consequences for health are low, the coach’s attitude is favourable, and the expectation of short-term success is high. The adults (70%) judged that the use of a nutritional supplement is acceptable only when the negative consequences for health are low. Among the adults, different ethical positions were found but they were not linked with the involvement in sport.