No AI understands irony perfectly, and even the most basic criticism are hard (“Thank you for the hair in my soup!“, ”Good riddance TelCo!”) However, it is iron

No AI understands irony perfectly, and even the most basic criticism are hard (“Thank you for the hair in my soup!“, ”Good riddance TelCo!”) However, it is irony because it's a minority use; words change their meaning if you use them too much in a different sense. This makes comparing the amount of both corpuses a crude, but relevant approach. For client work, I personally prefer to look at the length, and extend of vocabulary (Zipf rank, excluding misspellings, argumentative keywords) of the comments, because it's not really positive vs. negative as much as useless (praises or attacks) vs. arguments (usable criticism vs. structured defense) that matters on the long run. For relationship studies, I’d rather look into private messages and delay to respond (with, in Facebook case, a clear explanation that Scientist had no access to actual information, or even individual meta-data) than content.