I worked in a large public library service as a teenager (before the internet), rotated around several libraries, and noticed there were several patterns to readers choices in all of the different libraries. Almost all readers would stick to one or possibly two genres, fiction or nonfiction (minority). For example westerns, detective stories, romances, etc., non-fiction, history (usually a fairly specific period, war, or service (naval combat for example)), pop-science, etc.
Most people took 3 or 4 books out for a month (allowed period) and brought them back at the end of that period.
And then each library would have 2 or 3 people at most who read voraciously across genres, fiction and non-fiction (although not the easy lit romance, western, etc. books), applied for extra borrowing privileges, and would bring all the books back typically within a week or two.
There are many, many books out there that are well worth reading, and there are probably even more that aren't, but I suspect you have to read some of the latter to be able to get to where you not only appreciate the former, but can tell the difference by the book blurb/and or contents of first couple of pages.