Eye gaze is a powerful directional cue that automatically evokes joint attention states. Even when faces are ignored, there is incidental learning of the reliability of the gaze cueing of another person, such that people who look away from targets are judged less trustworthy. In a series of experiments, we demonstrated further properties of the incidental learning of trust from gaze direction. First, the emotion of the face, whether neutral or smiling, influenced the pattern of trust learning. Second, the effect was specific to judgments of trust; reliability of gaze direction did not influence other emotional judgments of a person, such as liking. And third, visuomotor fluency was not sufficient for learning of trust, whether or not the face served as a target or as a distractor. Taken together, incidental learning of trust is influenced by facial emotion, it is a specific effect that does not generalize to other emotional assessments, and it is not determined solely by processing fluency.