For all of the truly great posters out there, it's incredible how many really, really bad ones make it into cinema lobbies and online. It almost feels like studios now just hand the duties to interns given a crash course in Photoshop for an afternoon.
Perhaps the reason for that is the sheer number of really clever or marketable movie posters that end up either censored or banned outright. All that work to create a memorable image and the powers that be take one look and decide on the general public's behalf what will offend or sicken them. In that respect, you can probably understand why they'd just take the easier, inferior approach.
Thanks to the powers of the Internet, some of those banned marvels (and some that probably deserved to be banned) can still be found. So they might not be appropriate for outside advertising, but it's a far more grown-up place round these parts...
To a certain extent, all you want from a poster is that it sells exactly what the film is about with some emotive hook but without wading into spoilery waters and giving away too much of the plot. To that end, this provocative one sheet from vagina dentata horror Teeth hits the brief.
Even without knowing anything about the film, the sight of some very low-set gnashers would be enough to intrigue even the most hardened of horror film fans. It also serves as a warning for anyone of a weak constitution not to watch it. So really, it's doing everyone a service.
Sadly, the MPAA didn't agree and the poster was banned for being too naughty.