There is a large and corrosive gap between a heuristic–a profiling tip that indicates something or someone may need to be observed for possible misconduct–and stereotyping–deciding that someone is undesirable and is going to commit unwanted actions because of their identity. A man walks into a crowd at a speech and he’s scowling, possibly fingering a knife in its case–the idea that this man should be observed is based on logic fed by hints from similar past situations–a heuristic that is a shortcut and an efficient mental process that narrows the odds of error. Stereotyping increases the chances for mistakes.