The below thread on Dear Evan Hansen contains an interesting thought about familiarity with a score and how that relates to assessing it when seeing a show.
Personally, I avoid listening to a score (if a cast album exists) before seeing it on stage. I enjoy experiencing the score dramatically in the context of the show. Also, if I listen to a cast recording before going in, I will most certainly be able to discern the plot and any twists that may occur.
Revivals are another matter, but for a new show, I enjoy the surprise.