If you do some googling for trade libel you will find examples.

I base my opinion on a business law professor that I had respect for. It was outlined also in the book we were reading. His impression was that you must be able to prove that profits were lost, in any case, otherwise emotional distress.

http://www.lindawilliams.net/trdlib.htm

A heard a more relevant discussion on the radio the other day:

http://www.npr.org/templates/story/story.php?story Id=6249980