Everytime I read a review a show I've been to in person, I come away thinking the review really said nothing. Maybe it's just a Washington Post thing or something. As an example, take this review of the Old 97's show. You could say it's favorable, but the wording is so mild and bland, it might as well be saying, "Food is good." http://www.washingtonpost.com/wp-dyn/articles/A47710-2004Jan25.html This wording is about the only thing that attempts to give an impression: The rest of the review is more like background for the uninitiated.
They probably form an opinion and then write the review without going to the show - that's why they have to be so non-commital.