What does it mean to judge someone? Is it to form an opinion concerning the rightness of an act that someone performed? Or is it to form an opinion regraded the character of the person who performed that act?
If we are talking about the first concept, then if we have a moral standard that proscribes actions that other frequently perform, then we end up often judging others. But I don't see anything wrong with "judging" in that sense. The idea that we have to dumb down all standards of morality for fear of being guilty of judging others seems to me to be ridiculous (though popular). It is more difficult to draw inferences concerning the character of others, however, and so there is a reason to refrain from making these sorts of judgments. But very often we are told we ought not to judge, which ends up meaning we ought not to hold moral standards that would result in our disapproving of the conduct of others.