I'm not sure why you would want to use rumours to spread your brand name??? In other words your proposal is to make-up stuff... Don't they call that lying???
Rumours and gossip is more in the domain of celebrities but as brands, I really cannot see how that would work given the lack of appeal or worse should it be negative rumours then that is slander and deformation whereby there is indeed serious legal implications arising from such practices... Also dont forget the huge number of lawsuits filed against journalists, newspapers due to false rumours and slander when it comes to celebs...
A better way to promote your brand to the masses would be think of ways to get your brand to go viral through a campaign such as video, social etc... I would be thinking on the lines of a really funny/informative video, infograph or meme etc... Forget about making up lies and rumours...I am sure that it will not work as expected and further will come back to haunt you....
