Assessors' perspectives on their evaluative practices remain relatively under-researched. Given evidence that higher education assessment and feedback continue to be problematic, this paper proposes a specific methodological innovation with potential to contribute both to research and practice in this area. It explores the potential of a micro-analysis of textual engagement, nested within an ethnographic approach, to defamiliarize the often taken-for-granted practice of marking. The study on which the paper is based used screen capture combined with audio-recorded, concurrent talk-around-text to throw light on the processes, strategies and perspectives of eight teachers within one university as they assessed undergraduates' work. This close-up focus was nested within broader ethnographic data generation incorporating interviews, marked assignments and other assessment-related texts. The paper presents selected 'moments of engagement' to show how this methodology can offer a renewed understanding of evaluative literacies as complex, 'messy' and shot through with influences invisible in the final assessed text but which may nevertheless be highly consequential. The paper concludes by reflecting on the potential for this type of data and analysis to contribute to assessor development and inform debate about the future of higher education assessment.