I shamelessly admit that I'm a sushi snob. It's unavoidable. I lived in Japan for three years and ate some of the best and highest quality fish. The bar was set high. I have found many exceptional sushi establishments in the US, but unfortunately, I have also encountered a great number of sub-standard ones. Raw fish is just not something you want to mess with if you're not going to do it right.
An interesting article, Japan to certify cuisine but no 'sushi police, explains how a group of experts in Japan, with support of the Ministry of Agriculture, has launched a campaign to certify authentic Japanese cuisine overseas. According to the article, "Promoters unveiled a logo that will identify "real" Japanese restaurants overseas -- a pair of chopsticks holding a cherry petal set in front of a red rising-sun flag." Personally, I think it would be nice if all cultural food had some sort of authentic stamp of approval, but I would greatly appreciate seeing this logo in Japanese restaurant windows. I'm still reeling from the too thick semi- frozen piece of tuna I had a few months ago.
For more about this subject, as well as some great articles on sushi in general, check out Sushi Otaku.