The person who finds an anomaly must decide whether to doubt the instrument, the theory, or themselves.

An anomaly forces a choice about what to distrust. The reading is strange, so either the tool is faulty, the theory is incomplete, or you made an error, and nothing in the data tells you which. People tend to pick whichever of those three is least costly to their sense of themselves, and that tendency, not the anomaly, is what usually determines the outcome.

When something does not fit, name all three candidates explicitly before choosing. Check the boring one first, since instrument error and your own mistakes are far more common than a broken theory. But keep the third option genuinely open, because the anomalies that get explained away too quickly are how real discoveries get missed.