Is an unconstructive comment trolling.
Of course, it depends, but usually yes.
What it depends on is how you define unconstructive. Endless harping on about things I've heard gazillions of times before only serves to annoy me, hence I call it trolling.
Yes, I know some people think CAM is a scam because they haven't received their t-shirt/coupon. I see nothing wrong with having that opinion. But endlessly repeating it until it drowns out all constructive debate about how we as a community should move forwards doesn't really help the case, does it now? Of course, I personally don't believe much in the concept of revenge.
Other points:
Does the innocent and genuine praise of a chosen solution constitute trolling?
Well, if you ask like this, no. But there's a fine line between irony, sarcasm, fundamentalism and a few other things when you don't have anything except smileys (or lack thereof) to judge the poster by. For instance, I think very few posts appraising AmigaOS and claiming that Bill Buck is the devil (and using very BAD english as well) here and on ANN over the last few months can really be called innocent.
However, if I say that I have NO real interest in MorphOS but a lot of interest in OS4, from my personal (emotional and technical) point of view, then I fail to see how this can be considered trolling. Unless I would harp on endlessly about it when it is not contributing to the discussion, see the point above.
Presenting rumours like news? I consider that one of the worst kinds of trolling.
Mentioning something off topic isn't trolling as long as it is marked as such and further discussion is taken to a new thread. I know I could be better at this myself, so not complaining too much. But misters (in alphabetical order, mind you. I'm not saying either one is better than the other. They are both VERY VERY BAD) Alkis and Samface _certain_ should try to learn from past mistakes some day soon.
I think it's all a question of respect. I have a particularly bad feeling about moderators who take cheap shots at non-moderators in public, even when there is good reason for it. Some days it's necessary being a bastard, but you don't necessarily do it in front of everyone else (at least at my workplace my boss doesn't suddenly tell me I'm an idiot in front of everyone while we're having lunch. It also means I don't give him much of a reason to ;-) ).