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I'm not sure I can agree with that. Negative reviews are almost always far more helpful than positive reviews. Review sites should be careful about referencing positive reviews. The gold standard is Consumers Reports which is much more balanced than the average interent review site (where everything gets 4 stars) and thus much more helpful.
Speaking as an app developer, sometimes people get furious over things that are clearly stated before they download it. It really is easier to get complaints, I can see usage stats that show many more people using my apps daily.
Good reviews are worthless to me as a consumer. What I want are details, good and/or bad, that I can use to evaluate my purchase ahead of time. "This is great!!!", "I would use it again!" are devoid of information.
If negative reviews are more informative, then I assure you, you should welcome them over a bunch of five-star "great!"s.
Besides being informative for me, the user, they should be valuable to you, the business owner. Nobody maintains an "attaboy" database, but you better keep track of bugs and fix them if you expect to grow or even survive in this economy.