So, is the {mon} positive or negative ?

We don't know, but Okrand did talk about the word mon once:

The Klingon word for "smile" is mon.  This also means things like "snarl" and "smirk." I wouldn't be surprised to find a Klingon mon and growl at the same time, but mon by itself doesn't describe the full growling experience.

-- 
SuStel
http://trimboli.name