Someone criticises your intelligence. You brush it off. Someone criticises your integrity. Something tightens.
The specific point of maximum sensitivity is different for everyone — and that specificity is not accidental. It is a precise map of where the Ahamkara has invested most heavily.
The Yoga Sutras describe the ego-functions that maintain personal identity and the way these produce suffering when challenged. Dvesha — aversion — is specifically triggered by what threatens the identity structures built up as protection against the root feeling of incompleteness. The criticism that wounds most is the one aimed at the constructed self's primary defence.
Shankara's Vivekachudamani contains a precise description of the liberated person's relationship to criticism and praise: Nindastu stuyatam va — whether blamed or praised. The liberated person is unmoved by either because neither can threaten what they actually are. Not because they are indifferent to quality. But because the truth of their being is not constituted by other people's assessment of it. The assessment can be useful information. It cannot be the verdict.
The diagnostic use: take the criticism that most consistently produces the sharpest response. Is it true? Even partially? If it is, the pain is from the gap between the image and the reality. If it is not true, the pain is from the threat to the image. Either way, the pain is about the image — not what you are.