Miskatonic
Auror
I agree with Mindfire. I routinely look at the first couple of pages of a book and make a buy decision (assuming I've made it past the cover and the blurb). Moreover, I as an author do not expect the public to give me any better break.
That's why I found this thread worthwhile. I *do* want to make sure the blurb (and cover!) does two things. One, that it hooks. Two, that it does not repel. Both are important. I would not have thought samurai either, though if there was a picture of a samurai I'd probably put it together. It would be a negative, though I perhaps would not have reacted quite so viscerally. It does not take many such negatives, though, to drive me off.
There are times I let the rope pay out further. One is when it's an author I've previously enjoyed. That one gets more rope. Another is when it's a book that's in the genre niche where I'm working. I've grim-slogged my way through two or three books like that. But when I'm just reading for pleasure, my standards go way up. So those first impressions are terribly important, and it's quite enlightening to hear from fantasy readers how they react to these seemingly trivial points.
This is essentially what you have to do to try and sell a script to a studio. Basically have 60 seconds to convince them the story is worthwhile. Then you have the movie poster which has to do the same for the consumer.