Syag, that sounds pretty condescending. I don’t think people will say nasty things about a fellow member’s business, and I don’t think there is what to point to, to back up this accusation.
Nasty comments stem from the fact that there is no face behind the comment. You never (I hope) mock a person to his face while he tells you what he just thought of. On the other hand, if you read an opinion on a wall you will often wave a hand at it and twist your mouth. It takes time for new members to get used to the fact that there is a real person getting the feed-back.
Now, when you make a real connection to who you are that would actually stop natural, nasty comments.