We tell each other to avoid using stereotypes, but more than 50 studies have assessed the accuracy of demographic, national, political, and other stereotypes. Consider this article, for example: “Stereotype Accuracy is One of the Largest and Most Replicable Effects in All of Social Psychology.”. Excerpts:

Stereotype accuracy is one of the largest and most replicable effects in all of social psychology. Richard et al (2003) found that fewer than 5% of all effects in social psychology exceeded r’s of .50. In contrast, nearly all consensual stereotype accuracy correlations and about half of all personal stereotype accuracy correlations exceed .50.

The evidence from both experimental and naturalistic studies indicates that people apply their stereotypes when judging others approximately rationally. When individuating information is absent or ambiguous, stereotypes often influence person perception. When individuating information is clear and relevant, its effects are “massive” (Kunda & Thagard, 1996, yes, that is a direct quote, p. 292), and stereotype effects tend to be weak or nonexistent. This puts the lie to longstanding claims that “stereotypes lead people to ignore individual differences.”