The views expressed in Qercus are those of the reviewers. I've never told a reviewer to deal with advertisers' products differently from anything else.
If all a reviewer could say is "this is crap" then I wouldn't give it that much space. If a reviewer found lots wrong then I might ask them to offer a "what needs to be done before I'd buy it" type of review - and give the publisher the chance to say whether or not they are working on such improvements. The best is where a reviewer contacts the author/maintainer, suggests improvements, and by the time the review is ready some of those improvements are dropping through in updated versions of the application. I want reviews to facilitate development - not destroy any chance of improvement.