We all get criticism daily in our lives. We can ignore it, take it to heart or learn from it.
Which path do you choose?
One time I was painting outside at a park, a guy came by to look. He then peeked into a bag I had and told me those are not the pieces that interest him. He then listed the reasons why for the next thirty minutes. Keep in mind, I did not show him my bag of paintings. he opened it up to see them. I did not try to sell to him. I just listened.
As strange as it may sound, I considered my interaction with him a success. He spent his time talking about art. My art touched him in such a negative way that he needed to explain why. His why was not how to make the art better. His criticism was how it made him feel and what it meant to him. My opinion is if anyone's art make you think and say something unprovoked for thirty minutes, you should buy it.
When do you ignore the criticism? When it does not make sense to you. This may mean someone does not like the color blue and your work has blue in it. Do not change the work to another color. If the criticism is based on color theory, then take another look at your work.
Take criticism gracefully even from the most unlikely candidates. Even little kids have opinions. If they exclaim they love the dog in the picture, but you painted an elephant - then you missed the mark. It does not matter someone does not have an art degree or is a not a teacher. Stop, see, access and accept gracefully.
It is your choice to grow from critiques.