Teachers’ assessments of students’ academic performance are susceptible to various cognitive biases. The evidence for higher grades given for legibly than illegibly handwritten texts—the handwriting legibility effect—is partially negative in the literature, however. Three explanations for the negative evidence could be offered. First, the variation in handwriting legibility could simply fail to implicitly affect the graders’ behaviour. Secondly, the graders could intuitively associate handwriting illegibility with males and legibility with females. The presumed males’ texts could thereby receive higher grades than females’ texts, hiding the handwriting legibility effect proper. Third, the graders could spontaneously and selectively inhibit the handwriting legibility effect. In the present experiment, forty second-year teacher students graded fifth-grade students’ handwritten test answers. The answers varied independently in content quality and handwriting legibility. Handwriting legibility did not measurably vary the grades. Nevertheless, handwriting legibility became gender-stereotyped and, at a trend level, varied grading confidence. However, the gender stereotypes were not measurably reflected in the grades. This set of findings is best explained by the participants’ spontaneous and selective inhibition of the handwriting legibility effect. Spontaneous task-specific debiasing may, therefore, explain at least some of the previous negative findings of this effect in the literature.