there are quite a few like this actually.
Snake Eyes has a 5.9 but is really much better. One of Brian De Palma's better movies I think.
Barbarella has a 5.9. It's a fairly awesome cult classic.
Desperately Seeking Susan (5.9 again) is an 80s rom-com classic directed by Susan Seidelman. You'll find that quirky comedies and rom-coms and almost anything aimed towards a female audience is rated pretty low on IMDb.
Marooned (5.8 ) - fairly decent shipwreck drama set in space with gregory peck and gene hackman. was re-cut for video and shown on MST3K though so it is known as a "bad" movie. it's really not though.
Jumpin Jack Flash (5.8 ) - basically a classic at this point. but female fronted quirky comedy.
Cadillac Man (5.6) - actually fairly decent robin williams / tim robbins comedy. again quirky comedy.
Hannah Takes the Stairs (5.6) - pretty good greta gerwig / mark duplass mumble-core entry. recommended for fans of those two.
Buffy the Vampire Slayer (5.6) - kind of boggles the mind how this is rated so low. it's basically a classic. but again, female fronted quirky comedy.
Earth Girls are Easy (5.2) - ridiculous 80s sex comedy with Gina Davis, Jeff Goldbloom, and small early roles by Jim Carey and Damon Wayans. Used to be on cable all the time. but again, IMDb hates quirky comedy.
Ninja III: The Domination (5.0) - so bad it's good ninja classic. insane mix of way way way over the top ninja action scenes, poltergeist, and other random 80s cliches. really must be seen to be believed.
