How you receive criticism and your reactions or non-reactions are a great barometer for discovering just how much your ego is clinging to a particular desire.
I uncovered this insight not too long ago while receiving criticism from a stranger about my choice of attire. When she was talking to me, I noticed I wasn't reacting to her. I wasn't reacting because I didn't believe what she was saying, and secondly I wasn't looking for approval. I noticed the emotional freedom I felt because I wasn't wasting energy mounting my ego's defense against her words.
In this particular instance, perhaps my ego had let go of the desire to receive love based on my appearance. I didn't need her to love me for how I looked or what I owned to feel safe. Instead I just saw her words as a form of fear and a way of creating distance between us, which perhaps she needed to feel safe.
In other situations, when I am reacting to what people say or do, then I've begun to notice this is where my ego is still deeply invested in the outcome. My ego wants to control something or someone according to my own desires.
I think we've all encountered or perhaps been the person that has subconsciously or consciously poked vulnerable spots in others, looking for weakness -- an Achilles heel so to speak. The kind of person that would say, "I know how to get your goat," which translates as "I know how to arouse anger or annoyance in you."
When a person finds the secret thing another ego fears will be exposed or destroyed, they may become a sort of emotional arsonist, seeking to elicit a negative reaction through criticism so as to watch someone else set themselves alight and go up in flames.
Usually I try to escape these experiences, and I'm not suggesting to stay in unhealthy situations; however, if you do receive criticism that is designed to do more harm than good, it could be an opportunity to explore what your ego is clinging to.
Tuning in to your reactions and non-reactions when you receive criticism from others and getting curious about your underlying needs can give you a clearer picture of what your ego is still holding onto. This awareness gives you a chance to hang your ego out to dry so to speak and offers the possibility of letting go of desires that may no longer serve you.