If the cap fit, wear it.

A person who recognizes themselves in a criticism should consider whether it applies to them, even if no one has named them directly.

The proverb can also push back against someone who takes offense at a general remark: their reaction may suggest they see themselves in it.

Use it in response to a broad criticism or description that someone treats as a personal accusation. It can sound pointed, so it suits situations where that challenge is intended.