Popular wisdom says we should not judge others at all. But in John 7:24, Jesus specifies both what is permitted and what is not permitted in the realm of human judgement: “Stop judging by mere appearances, and make a right judgement.”
So we can’t judge on “mere appearances,” but that doesn’t mean we can’t judge. “Make a right judgement,” says the Lord. Well, what kind of judgement is that? Whatever it is, is will not be on the basis of “mere” appearances. We shouldn’t just presume anything about somebody. The judgement will be appearance + something else.
What would that “something else” be? Well, I’m not sure. Maybe it is a more objective standard, like getting to know the person, and working from “within” their circle of trust. With a knowledge of the person, and having earned their respect, I think judgement could be constructive.
If we weren’t ever allowed to judge, how could we help others? How could we reprove sin, or evangelise? Obviously, some judgement is good. It just needs to be done in the right way.