There are several reviewers on here that cover bad movies, from big budget bombs like Battlefield Earth to obscure crap you've never heard of. The best ones are The Nostalgia Critic (he sticks to mostly 80s and 90s stuff, not all he covers is bad), Phelous (mostly bad horror movies), Cinema Snob (mostly obscure horror and action movies), Film Brain (bad big budget movies), Mike J (bad sequels), and Spoony (alternates between video games and movies, usually geek lover movies).
I will warn that the language can get pretty blue depending on the reviewer.