Either way it is an easy way out and a lazy move. People use it to bluff others by pretending like there is much more to say, when in reality they can't think of anything to add that is important or useful.
Mostly used by people who desperately want to feel superior, but lack the actual supporting information to be superior in an argument (or even contribute).
When you say "nuff said" you are letting people know that you are not able to have a normal conversation, and cannot accept anything against what you believe.
My *car name* is faster than yours, nuff said. (Why?)
*Game name* is the best game ever released, nuff said. (Stupid)
The phrase can also be used between peers to acknowledge understanding of a pre-emptive statement or question that would justify a lack of further explanation.
Answer: 'Nuff said, man. Total trainwreck.
I hate that food. 'Nuff said!
I'm the best. 'Nuff said!
For cool subects:
It's Megan Fox. 'Nuff said!
It's a Ferrari. 'Nuff said!
Friend: Why? I'm stupid and don't understand what you mean...
Guy: Remember?! My girlfriend is abstinent, nuff said!