What is the hardest part of an art critique? what strategies can you use to you with this part?

In my opinion, designing an art critique varies from individual to individual because it solely depends on how one perceives it. People from different backgrounds would identify and analyze an art according to their vision and exposure and so everyone would have a differing opinion. However, an opinion can never be correct or incorrect so analyzing the artwork would further rely on what justification is provided for it and that is the strategy I think one should go with: to look for the logical reasoning behind an interpretation of an art work.