Forums in many ways are an absolute nightmare, I've seen many a shocking thread where people's grudges and lies have done massive damage to a business before they've even got wind of it and had chance to do anything about it.
As an example, a girl got thrown off a forum for very cleverly manipulating people into witch hunts. She'd get all doey eyed, hint at being hard done by and get an idiotic group of fanboys to cause grief on her behalf. She'd act all innocent and suggest being given things for free and posting threads about how great this business now was would help shut things up. When it all came out in the wash, there were blatant blackmail threats from her to a few companies, countless thefts of stuff supposedly never arrived, credit card fraud - a real mess.
Thing is, if she'd come up to you at a meet and slagged a company off you knew were decent, you'd have thought her an idiot and ignored her. Yet somehow the internet gives people a powerful voice and others want to believe it.
In other ways though, people are their own worst enemy. I've seen someone bitching about an insurance company, for them to then go and cancel their policy and refuse to cover them ever again. Ha! The doink who crashed that VXR at Brunchen II who was covered on his German policy (Army serving out in Germany) and then went boasting on the 'net he was timing, they then refused to pay out...
The internet. As dangerous as it is useful.