From what I can see, most reviews have no great impact on the sales of a given title by themselves. In aggregate, it’s possible to see an effect, but only in a “Rotten Tomatoes” situation where every review is similarly damning or similarly laudatory.

I’ve lamented a number of times about how I wish that there was a better standard of review available somewhere. Most of the reviews that I read aren’t what would typically be considered reviews at all—they’re more like blog postings. Not a lot of genuine critical faculties or technical knowledge or analytical thinking is applied to most reviews, it seems. They all come down much more simply to whether the reviewer liked the book or not on the most surface level.

There’s nothing wrong with any reader expressing their opinion, but I’d love to see reviews that set a higher standard. In those cases, when a reviewer’s word comes to mean something, comes to stand for something, then the reviews can have a chance to affect their readers more readily and to affect sales. You can see this with certain storied reviewers and critics of film and prose and television. And I’d love to see the same for graphic fiction.