After decades of research highlighting the fallibility of first impressions, recent years have featured reports of valid impressions based on surprisingly limited information, such as photos and short videos. Yet beneath mean levels of accuracy lies tremendous variance—some snap judgments are well-founded, others wrongheaded. An essential question for perceivers, therefore, is whether and when to trust their initial intuitions about others. In three studies of first impressions based on photos and videos, we examined accuracy for Big Five trait judgments as well as corresponding reports of confidence. Overall, perceivers showed a limited ability to intuit which of their impressions were more accurate than others, though a curvilinear effect emerged: In the relatively few cases where perceivers reported an absolute lack of confidence, their accuracy was indeed comparatively low. Across the studies, judgment confidence was shaped by sources at the judgment-level and the judge-level that were unrelated to accuracy.