Star Trek

There is a valid point putting it either way so it gets a little clumsy when trying to distinguish the types of emotions.  It's not necessarily bad, but is generally regarded as such.

This actually reminds me of something from a Star Wars video game, Jedi Academy.  The player controls a character named Jaden, being trained by Kyle Katarn.  In an early stage, Katarn says that force powers are not inherently good or evil, that it matters more how you use them.  The non-core force powers are divided into light & dark side. 

I think you are over-analyzing it.  Yes, the wording is clumsy, and therefore leads to contradiction, but it is, as you called it, a matter of semantics.

I believe that emotions, like everything else in life, obey Newton's law that every action has an equal, but opposite, reaction.  One type of emotion seems to be balanced by the other, at times.  However, I prefer positive emotions to negative emotions.

Well. my short answer would be: Troi's first speech is wrong. There are negative emotions -- (clearly, emotions that an organism is designed to avoid; socialisation and operant conditioning rely on the positive / negative split in feelings.) I don't think that her speech establishes a lack of negative emotions in TNG -- hers is just one of a number of possible perspectives or theories. (An incorrect theory, to be sure. But perhaps what she means is that Data's anger is not inherently evil.)

Well I personally don't have all that much faith in Troi's counsoling activities ever since I saw "These Are The Voyages..." Not sure what made her think that sending Riker into the 24th Century version of a film based on real events would be more effective than actual COUNSOLING but hey....

As for continuing to call them negative emotions, I think it was most a writer's conveniance or oversight. Had they just been called emotions throughout the episodes, it might come off as though the message to Data is all emotions are potentially dangerous.