The Dimension Collector's Series DVD cover has the fanged face of a vampire woman on it.

If someone thinks it's ruined because they found out ahead of time that there are vampires in it... yeah, that's their problem.

If it's in the trailer it's fair game. Besides an actual spoilery description for From Dusk til Dawn would be all the non-vampire parts. The "twist" is that a movie billed as Robert Rodriguez vampire schlock actually has an entire other movie contained in it. That's a bit of a spoiler I suppose, my bad.