That would be very difficult to determine. I do think that the internet gives people a sense of anonymity and that seems to make people more outspoken, leaving rules behind. For example, I might be reluctant to voice a controversial opinion in a crowd of people who might disapprove. But online, we can voice opinions, even act outrageous with no repercussions.
So I think it is highly likely that there are a lot of online stories, views and opinions that may not be genuine.