"Don't judge" is a rather unintelligent phrase. As I pointed out in the title, it happens automatically. We judge to discern whether we should apply the behaviors of others to our own lives. It also helps us determine whether we should let those people be influences in our lives. We also judge people indirectly by what they create, i.e. writing, music, buildings, etc.
Furthermore, "judging" of sorts is present everywhere in the animal kingdom. Consider how many animals form dominance hierarchies by sizing each other up and fighting each other. Life is also the ultimate judge by determining what genes survive and which don't.
I'm not saying be a hypocrite, but it is important to judge others, lest we end up in a place we could have prevented just by observation.