When I say this, it shouldn't come as a great surprise, especially those familiar with the Greater Internet Fuckwad Theory, first presented by Penny Arcade in 2004, and which has since grown to an official academic name (online disinhibition effect, though outside of academic journals researchers still just go with Penny Arcade's term) and which has caused Wikipedia to make the most wonderful equivalent graphic anyone has ever licensed to Wikipedia.
And I presume you are getting increasingly familiar with the practice of name-and-shaming people who have made terrible, terrible tweets, often as basically the entire content of an article... an article type which Ben Kuchera, from, yes, the Penny Arcade Report, is seen here decrying. Twitter users are not, generally, anonymous.
According to a recent study at Beihan University in China, they don't need to be. A team led by Rui Fan took a collection of posts on China's premier social networking site, Weibo, between people who commonly contact one another. They were looking for posts that had been, well, retweeted (Weibo's commonly compared to Twitter), and matching posts to emotions: specifically, anger, joy, sadness and disgust. The aim was to see if there was any sort of trend as to what emotions got reposted. And lo and behold, here's that big shocker, the only emotion that was reposted to a significant degree was anger. Basically, people repost stuff that pisses them off.
The big question raised after the study was, is this just China or is this the case in the West as well. Most denizens of the Internet could save them a lot of time and energy.