Well, I haven't done exactly that, but I think I've done something else that will serve the same purpose. Now, every review will have a tag that has the format of the item (i.e. book, film) followed by a colon and its genre (i.e. science, comedy, health).
You can then look to the list of tags in the right toolbar and click on the classification that interests you (like TV:Comedy). You still will need to sift through the other tags, but since the list is alphabetized, there shouldn't be trouble.
Thanks for the idea, Eric! And if anyone else has thoughts, don't hesitate to share.