No badly written is objective, see in the real world we have years of class we call English or probably whatever language for your country or area. This class teaches you all the rules of how to write well; funny thing its called grammar pretty sure you were exposed to this in your schooling at some point.
Grammar, syntax et al is objective, (unless purposely done 'bad' to mimic dialect).
Themes, character and plot is all subjective.
This is also why I pushed to have a proof-reader and editor because:-
A.) I hate proofreading and editing, while I do it as best as I can before submitting, it's very tedious.
B.) Given the excessive amount of words written, my eyes now gloss over mistakes.
C.) As I explained to Uber, any professional writing goes through a proofreader/editor.