First of all, "Judge not lest ye be judged" refers to hypocritical judging. If I told you shouldn't cuss, while I was using cuss words to say that, then I would be a hypocrite, that would fall under "Judge not lest ye be judged." To take it out of context and say all judging is bad? That's not right.

If someone were to come up to me in real life, and were smoking cigarettes, dressed in some crazy goth outfit, and were saying the F word every 5 seconds, would it not be okay to judge them? I can certainly look at person and judge, and be like, "yeah that guy is totally not a Christian".

Now it wouldn't be okay if the same story happened, but the guy was some normal regular person, and I couldn't tell what kind of person this is. That's when it's not okay to judge him.