So you take the book off the shelf, looks interesting, flip through it and look at the bar meter in the upper right hand corner as it goes up and down. At high points, you stop and browse those pages because that meter shows that area was voted as most interesting by the readers.
The input would
be from people reading the online version of the books and moving the slider at the bottom when they read a part they really like.
For instance, the Star Wars novel would have a massive bump where Darth Vader said he adopted Luke Skywalker or whatever.
Conversely you'd just skip the low meter sections. If after glossing over the high sections you're sold or not, you can make your decision to buy or not, and if there's no high sections, or low sections for that matter, well, that's indicative as well.