We explored people’s reactions to expert categorizers who expressed difficulty in making a categorization decision. Specifically, we compared people’s impressions of expert health professionals who either expressed certainty, uncertainty, or ambivalence about a categorization decision in the form of a diagnosis. We found that ambivalence resulted in the most negative impressions of these experts, including lower ratings of competence and decisiveness (Experiment 1). Impressions of ambivalence did not improve when the complexity of the decision was explicitly manipulated (Experiment 2). Implications for categorization are discussed.