My wife and I both recently posted negative reviews at businesses that were advertising with Yelp.  Neither review (which were both fair and truthful) ever showed up on site.<p>edit: Just to clarify, I spoke to Yelp about it.  The reply I got was "[The] spam algorithm can filter based on how established user is. [Your post was] not deleted &#38; can re-appear on biz page. Still live on your profile."