There is a big difference between ESL forums where learners can come for help with their English and those where people discuss specific schools. I only really have experience of the former (this site). As far as the rest of your post is concerned, whilst I agree that there is little comeback for people who are wrongly criticised on the net, I would prefer to have the ability to search for information, sift through it and use my common sense to decide, on the balance of probabilities, what the truth is.
It strikes me that your post is one of personal experience which is unfortunate. In the main, however, I find no overwhelming reason not to take ESL forums seriously.