It is worth some research to make sense of this issue, as the importance of judging and being warry are manifest, both in scripture, and in reason. It is nonetheless also manifest, from the same sources, that the activity of fault-finding is wicked, and how to distinguish between right conduct and improper conduct is made to seem somewhat uncertain.

At this time, I would venture that fault-finding consists in the activity of identifying weaknesses in others out of pride or covetousness. Perhaps it may also consist of, or extend to, imagining faults that we have no right reason to imagine. (Such, for example, I seem to have seen become a staple of news media reporting of the decisions of certain disliked public servants. Everything is labeled a weakness and everything is reported in a negative light, whereas another preferred public figure may do some very similar thing and have it spoken of as a strength.)

Good judgment, however, would likely be free of pride and covetousness, and would be characterized by proper application of right principles based upon sound evidence.

Anyhow, more keys for discerning proper conduct in this regard would probably be useful.

A similar dichotomy is likely present in the admonition to not gossip, and the admission that it is incumbent upon he who has been warned to warn his neighbor. We are to proclaim truth but are to refrain from vain janglings.