I see. I think we are both right. Understanding the motives of the speaker is indeed crucial to actually accepting the criticism. My assertion is that objectively considering motives is practically impossible when you haven't installed the habit of recognizing criticism and pressing "pause" on your response.

If Bob isn't really bothered by the criticism that his breath smells, then he'll have no trouble stepping back and considering why Sally said that. Maybe the bad breath example is too specific - replace it with something that it would genuinely upset you to hear. Or maybe you're more sanguine than me, and criticism doesn't bother you much in general. Criticism does get under my skin. When I'm caught off guard by it, it's already too late for me to analyze the speaker's motives, because my analysis is really just a hasty search for reasons why they're wrong. I think this is the general phenomenon that is the topic of this post.