Here is an example (my own) of how to make a comment about business minutia on HN.
http://news.ycombinator.com/item?id=2863071
Don't write like you are some sort of genius because you know more about accounting/finance/ops/whatever than people on a forum which is predominantly engineers. ("No, no, no, no.")
I added a framework for valuation and accounting which is a much more accurate than what was written in the article and in a fraction of the space.
The point I am making is very valid and extremely important for people to read after reading that article which is completely wrong in almost all ways.
I'd write it again anytime and gladly be downvoted in the off chance one person reads it and is saved from making huge errors later. (I will skip the "no, no, no" part and adjust tone to keep from seeming arrogant.)