Is a passion for truth. Sure, the "t" word might be subjective to some folks. But copy editors work under the assumption that a "best" exists. We might even reach it if the deadline weren't so damned close.
For the "best" version of a story is the one that tells the truth, to the best of our knowledge. We strive to depict the world as it exists around us, in the most proper grammar possible.
No culture war positioning here. Just constant, curmudgeonly striving for accuracy.