When one person makes judgment on another person's behavior,beliefs, attitudes, appearance or lifestyle, this usually falls into one of two categories.
I. Authentic Judgment
Authentic judgment here simply refers to the extent to which a person's actual emotions correspond to their expressed emotions. Within authentic judgment, there are two subcategories:
This is probably the nicest kind of judgment insofar as the person's heart seems to be in the right place. This is the sort of judgment we make when we see someone is doing something bad for them, and, due to our intense involvement, make judgments about the behavior in the form of very strong opinions about what they should or should not be doing. For example, if we have a friend that is in an abusive or exploitative relationship, and we find that we can't not speak up, and maybe are even a little bit blunt about it, but it's done out of our deep concern and involvement with our friend's life, that's enmeshed judgment. It can be suffocating at times, and perhaps even a little bit co-dependent, but the person's heart is in the right place.
Less generous, but still an authentic judgment, is when we judge others based on our own values. So, if we judge someone for giving up their pet because we believe that pet responsibilities are of vital importance, that's a value judgment. It can come off as a bit harsh at times. It is authentic because the person making it really feels that way.
II. Judgment As a Mask
This is when someone expresses a value judgment but the behavior is really eliciting some less socially acceptable emotion, such as self-interest or jealousy. For example, judging someone for a lifestyle choice can be a way of masking jealousy. Another example would be criticizing someone else's principled action as immoral or inappropriate not because the person really thinks this way but because the two parties are working at cross-purposes in some way. One instance of this might be a reporter who is discouraged from doing an expose on a corrupt practice (say,on the grounds that a lot of job loss will occur if they do) when, in fact, the editor has a family member involved in said practice.* They cannot simply say that they have a conflict of interest, so it gets couched in moral language to make the more idealistic person feel like they're the ones doing something immoral. The intent is to make the person stop doing the thing contrary to the other party's self interest through the instilling of guilt and self-doubt.
The really insidious thing about this is that the more idealistic you are, the more susceptible you'll be to this. People of a more cynical bent will be more attuned to motive, and to the possible disparity between spoken words and actual intent. To those who are more trusting, it can easily be mistaken for I-B.
*This may only happen in the movies, I'm not sure. I was trying to think of an example that would get the point across clearly without being self-referential. That was the best that I could come up with.