What is 'the current state of the art'? Note that I am a total dilettante in the area of machine learning/NLP.

And why couldn't the top k HN users (patio11 et al) be given the option to classify comments {dismissive; troll; shallow-cheering; ...;} and this human classification could be the training set of a supervised learning system that could use NLP algorithms to derive useful metrics. Simplistic example: dismissive word ('sucks'; 'never work', 'impossible') density correlating to something that has been flagged as dismissive. Or is this an impossibility? Again, I do not have the hands on knowledge to be able to call this one.