[metrocartockasur]

^That makes it clear that it is not considered backbiting, but does that necessarily mean it's okay to bring the sins of an open sinner up in conversation if it is for no beneficial purpose and simply done to look down on the open sinner?

There are pleasant actions of obedience and there are unpleasant actions of, again obedience.
It is pleasant to prostrate before Allah (SWT).
It is not pleasant to indulge in act of cleaning after going to WC.
Talking about someone's sin, when he or she is a sinner, is not a pleasant thing to do.
We believers are supposed to change a bad thing by action, by words or in our hearts.
A sin is a bad action.
Companions (RA) too physical action against people not paying Zakat.

I hope it clarifies the matter a little bit. And Allah (SWT) knows better.

PS : Looking down upon a sinner is an additional act. This is not appreciated in Islam.