I normally try to avoid polls, but when I feel strongly about the subject matter, I'll chime in.
In this case, I often gauge whether to purchase a product based on flavor text.
While I like the occasional piece of flavor fluff to bring a scene to life, a paragraph here or there, what I really detest is long, drawn out, not thought out descriptive passages in an adventure. Particularly paragraphs of laborous descriptions of what the adventurer's see, often describing how they feel...
".. the damp cellar door fills you with dread at the sight of the arcane runes carved into its surface as if by claws."
While that example might be ok in and of itself, there's usually a lot more, and the phrase "fills you with dread" presupposes far too much about the characters. Maybe their hardened adventurers who don't feel dread. Maybe their clueless students who are too baffled to feel dread. Let emotion occur naturally, not forced into an adventure via the accompanying text.
I love the one-liners, the quotes, though. They are humorous and still set a mood, without adding a lot of wasted space. I don't think they're as suitable for an adventure as they are for a splat*book, but quotes from an NPC are often just as useful.
Hope that helps.
Greg