Man let me tell you that every forum has at least one. They lurk around and can't wait to criticize, insult or offend someone. It must turn them on or something. As far as I am concerned, forums are communities focused to assist one another and to learn from. These kind of weenies are the capital criminals of forum society. It happens everywhere in life and like everywhere, they are not wanted or accepted. You will find that the "forum criminals" are more than likely serious under achievers and social misfits that hide behind false identity ( Avatars and usernames). Faced with real life situations, they will not have the guts to expose themselves.
Anyway, I normally ignore any input that is not constructive or contributing to the quality of life but forum stalkers are my pet hate.