It's always the movies where the producers have an idea of making some kind of mutated animal but they don't have the money to make it look good so the movie turns out to be shit.
Basically anything made by The Asylum fits into your category, as they spoofs made to fool people. Many of the films on here made by them, including this one:
(The Asylum making this movie is enough for you to see how freaking ridiculous it is)