Same Problem As Firefly Bad marketing. The problem with the series Firefly was NBC advertised it as a comedy, when what it was is a Sci-fi series with a lot of comedic relief. People who would have loved Firefly didn't watch it because Scify fans want their Scify taken seriously, if it makes them chuckle, all the better, but serious first.
That's this movies problem. The people who would love this are Murder Mystery folk, like me, and not generally Tarrintino fans, which I'm not. And most QT fans told me to pass. I loved Kill Bill and Pulp Fiction, but I'm not what you would call an QT fan. I find the way he tells story somewhat lazy, and his fetish with rape is not my cup of tea, no offense to QT fans, I 'm just not into QT's 'style' of filmmaking because there is way too much unnecessary rape and gratuitous gore, but I love the Hatful Eight because it not's really a Tarrintino film, it more of Columbo / Agatha Christi film with a Tarrintino twist.
Loved it, just wish I would have known 9 years ago what it was.