I look at the threads as booths that are set up on the public street, like down at Venice Beach, CA. There is a certain amount of territoriality that exists, so you can decide what products you are selling and you can put up your poster about buying U.S. Savings Bonds, but if someone comes into your booth and says that your merchandise looks like crap and that they think that buying U.S. Savings Bonds is foolish, you don't really have the right to throw them out. However, if they start breaking your merchandise or pulling down your poster, you have every right to stop them.
And of course, if somebody puts up a booth right next to yours that displays customer complaints about your product, I believe that you wouldn't have any right to stop them.