That’s what happened in the case of the book The Girl with the Dragon Tattoo.
IMHO, the book itself can be a bit of a go. The translation is awkward. Perhaps it’s just British English, but it still didn't seem smooth. "She married someone, never even introduced him to the family, and anon they separated." Anon??? Or "Every family had a few skeletons in their cupboards, but the Vanger family had an entire gallimaufry of them." I guess "gallimaufry" means hodgepodge. Leaving aside how many readers actually know the word, doesn’t seem like the right word. It seems like it should be something many times bigger than "few."
One way the publisher helped make this a bestseller is that they sent out tons of advanced reading copies. Even the ARC had a beautiful translucent cover. In an ad in the NY Times Book Review, they even offered a free copy of the thriller to anyone who wrote asking for one.
Read and even hear more here . One thing the NPR story doesn’t mention (at least in the print version) is that the book has an eye-catching translucent cover. Even the ARC is a work of art.