The amount you tip is a mini review.  This is your way of telling the restaurant how they are doing.  The waitress can be amazing but if the restaurant sucks the tip will be minimal.  Even a good restaurant can fail to get a good review.  Good reviews are very difficult to come by as people are way more likely to complain.  To praise a business is very rare.  I would say that the tip is the best way to tell if the restaurant is good or bad.  Createurs De Luxe is a good restaurant but can see a better review.