Part of our ReachCAST service is to give you, the Baltimore/Washington DC business owner advice on how to minimize the "damage" done to your business via negative online reviews and to give positive reviews a megaphone to be heard by the masses.
Advice we would definitely NOT have given was to go on the offensive on Yelp and attack clients and/or people you feel work at Yelp and bashed your company because you did not buy advertising from their sales rep. FTR: I have no opinion on whether or not this is a common practice for Yelp employees. There is a way to combat negative reviews on the Internet by smothering them with love NOT by throwing Napalm on a smoldering match. Business, especially restaurants, can live or die by their reviews.
Either do it right or hire someone to do it for you but do not get online, half-cocked and ready to explode. The only person you will kill is yourself!