You could always use a consultant like the one at badreviewhelp.com
on cruise critic, i've seen the owner come in behind and post follow up comments.
What the heck is yelp?
There are always people that you just cant please,.. you knowmthe circumstances. I wouldnt worry too much as your satisfied cutomers would outway this guy. And if you are worried he will spread it around, others will already know what an A hole he is and probably ignore it. Plus you dont want any more customers like him to walk through your door. My ex boyfriend worked in advertising, they used to say any publicity was good publicity,.. so at least it may make people wonder what your business is all about! LOL
add a filter or review each posting before it's published... you never see a negative comment on most shopping channel websites for just that reason....
Well, I'm not sure about yelp but on most websites that allow people to add comments or have any kind of comments area teh admin can filter comments to exclude those with key words such as bad, hate or phrases like "don't buy" etc.. Others are set up so that comments must be approved before they appear on the site where anyone can see them. Talk to a yelp admin or put up your own website and take control. Can't really help you more than that sorry. Hope it works out for you.