This article provides a reflexive account of the authors' experiences of the ethical challenges in conducting a higher degree by research (HDR) supervision project prompted by the ethics review process in a major Australian university. The authors also raise epistemological questions about the specific focus of the study, given the interrelations of ethics and epistemology. The project aimed to examine the conceptualization of 'poor supervision' by HDR actors including students and graduates with a view to informing supervision practices. The article seeks to highlight fundamental questions about what is researchable/unresearchable from ethical as well as epistemological points of view, and who can decide on ethical norms and boundaries in this research space. As HDR education in general and HDR supervision in particular have come under increased scrutiny nationally and globally inviting more research and academic engagement, such an account may be useful in pointing to the complexity of pedagogical, epistemological, and ethical issues and their complex interactions against the processes of institutional ethics review.