A lot of the on line social interaction is pretty one dimensional, there is very little context to the conversation. A person cruising a post and see's a remark like
"Dude, you are being a dick"
That is all the see, they do not see the context in the statement. Walking down a sidewalk and hearing someone use that phrase, the walker has time to gain some context of the situation friendly banter or fist about to be flying. On line there after several other comments possibly or not being willing to go back on search and see if it was in jest, or what, all they see is a rude statement made by one user to another user. Opinion is formed.
Context is very important, and it is seemingly difficult for people to remember what all is context. After all we have all seen how Media take one line out of a speech or a statement, and twist and turn it into what they want it to be.
Being friends on-line is not an easy road for people to travel mainly do to others not knowing the context of the on line friendship.
Context is important and you are right about the media taking lines out of context. I think this is the main position of the average troll too - to be as uncharitable as possible and add unintended and false context.