I think the majority of the negative chatter comes from former posters here who were Banned over the years. If they feel they were wrongly banned they will use other forums that are more 'forgiving' to lash out and voice their frustrations at whatever and whomever. Just like an employee who feels he was wrongly fired from his job, will often lash out at the former employer and even former co-workers.
There has been dozens and dozens and dozens of posters here who've been banned, and many were supportive of the stock up to a certain point before they got frustrated. I can't think of any other Agoracom forum that has banned more people than this one. I think there is a very solid connection between the ongoing negative chatter and the bannings here. Just my .02.