How book recommendations work

From my family and friends who read/liked Dan Brown and/or Clive Cussler (and/or Twilight, 50 Shades, and countless others) footnote

From my friends who only read based on the NYT Best Sellers list:

From my friends in the publishing industry:

(I take NO credit for the originality of this post or the gifs contained herein. Please see here for the original I have shamelessly ripped).

footnote I have read all of these books. I have even posted a review or two. I do not deny that these books have an appeal to a certain audience, they just aren’t for me.