There is a (crude) saying- "Arguing on the internet is like competing in the Special Olymics. Even if you win, you're still retarded."
While this comment isn't quite PC, it does have a valid point IMO.
Some people live for arguments. It is the only way they know how to communicate. I usually avoid these people and indulge my self righteousness in thinking I've taken the high road.
In general, though, I try to read every comment as if the author were smiling at me and chuckling while explaining their side. It tends to lessen the impact on me- I don't get riled up as easy. I also try to elicit the same jovial response in my reader's mind with the words I use and how I go about making my points.

/I took too many 'interpersonal communications' classes in Jr. College