Educational exclusion, as reflected in school dropout and school failure, is a major concern for the existing educational systems due to the negative impact it has on girls, boys, and young people from society’s most vulnerable sectors. Although current research reveals the various subjective, contextual and systemic variables that may affect the student who eventually fails and/or drops out, little is known about the determining factors as well as the actual meaning of this exclusion from the perspective of the students themselves. This paper reports the results obtained from a hermeneutical-interpretive study of the configuration and assessment of the figure of the teacher as perceived by students at risk of dropping out. A total of 49 semi-structured ethnographic interviews were applied to these students, revealing a series of characteristics, attitudes and practices that lead the interviewed students to build a dichotomous notion of what a good or a bad teacher is.