With state-wide administered large-scale assessments of competencies students' solutions of test items are independently coded by their teachers according to an instructions manual. The study at hand evaluates whether lack of conformity to the manual by the coding teacher goes along with aberrant responses in the psychometric model of Rasch (1980). Answer sheets of both low and average fitting classes from a state-wide administered large-scale assessment in the German state of Northrhine-Westfalia were re-analysed, and model fit was re-computed. Results show that (1) low fit is correlated with lack of conformity to the manual and that (2) higher scoring ability estimates were computed when being attributed to this lack of conformity. Concluding remarks are given for the work with large-scale assessments of competencies.