Half body horror and half lesbian romance, Lucky McKee's Sick Girl is bursting at the seems with underappreciated cinematic talent. While much of McKee's filmography is dedicated to the lowly weird girl, his best-known work being May (2002), I think Sick Girl is where his cinematic skills come together best.
Let's start with the talent, because I have a lot to say that's contrary to popular opinion. Erin Brown, while constantly being brought into the conversation to say she cannot act, is nothing if not committed to her role. If you've ventured into her filmography, you'll see that she isn't afraid to get weird (have y'all seen Dickshark), and so she jumps into bug posession and lesbianism with such conviction. She also has features that are actors on their own. Her piercing blue eyes shift from endearing to freaky depending on what the scene requires, and her long hair is both mesmerizingly elegant, and reminiscent of the girl from the ring. When combined, they work the horror comedy to their advantage.
Then you pair her with Angela Bettis, who is one of the most under-appreciated actors I've ever seen on screen (her horror scream at the end of this movie is one of the best), and it only amplifies Brown's performance. Bettis transforms into the awkward, socially inept Ida, and in her deliberate choice to play her character this way, makes Misty's more awkward line deliveries look like they're intentional too. Together, the two play off each other perfectly and, outside of their obvious chemistry, that shines even beyond their characters' clumsy natures, enhance each other's performances. (Also, sorry, but sometimes bad acting just adds to the autism coding,,, Oh, you don't speak how people expect you to? Girl, same. This, however, is a bias I am not including in the argument, no matter how comforting it is to me, personally.)
Then McKee comes in with his directoral flare. Combining his distinctly 2000s style with the influence of 40s powerhouses Emeric Pressburger and Alfred Hitchcock, he creates a unique visual experience that should not work as well as it does. It is this deep understanding of what makes a movie good that truly earns him his place as a Master of Horror.
I will also add that going into a lesbian film directed by a man is almost always scarier than any horror movie will ever be, but McKee handles Ida and Misty with so much respect. Their romance is soft and silly, and while there is a particularly steamy scene, it is within reasonable bounds, and feels so far from exploitative. This is the reasonable progression of a drunk, lustful, first night together, not the director's sick fantasies. And any other moments they have together, we don't see. They're mentioned off hand, or we fade to black, which is again in the spirit of the 40s films McKee is trying to emulate.
And this doesn't even include McKee's script, which is simply FUN!!! The humor is certainly for a specific type of person, but that type of person is me. It's very unserious, which makes the cheesier portions fit right in. In fact, McKee wrote in a lot of Hlubik's scenes while the two were drunk, which totally checks out when you watch them back with this knowledge. Besides that, though, McKee creates a very thoughtful metaphor about the dangers of moving in with someone too quickly, suggesting that, while it isn't inherently bad, it WILL have its road bumps, but with patience and kindness, these things can be worked through, and two people can live together in harmony. He is also very clever in how he subverts expectations. Horror movies like this typically end rather devastating (see Cronenberg's The Fly), and lesbians in horror tend to get the short end of the stick on top of this (bury your gays), but McKee gives Ida and Misty a happy, comfortable ending, following in the footsteps of other horror anthologies like Tales From The Crypt, which usually concluded its stories in the last way someone would expect.
As a final point, I love the practical effects. The bug design and transformation are so simple but so effective. And Misty's gooey ear!!! Beautifully yucky!!!