- How interesting/relevant (to me, anyway) the subject matter is.
- How well it’s written - that matters just as much in non-fiction as in fiction.
- If it’s research-based, how well it’s been researched (I do look at the footnotes).
- If it’s about a subject that is or may be at all controversial, what others in the field have to say about it.
I’m far more likely to read a research-based biography than I am an autobiography, but that’s not a universal rule for me. I’m not interested in autobiographies or biographies of so-called celebrities. The biographies on my bookshelf include books about my favorite 18th- and 19th-century British and American writers, historical figures (e.g. the Tudors, Eleanor of Aquitaine), and interesting/influential women (e.g. Georgia O’Keefe, Victoria Woodhull).
I assiduously avoid what I call political nonfiction – the kinds of books written by politicians and so-called pundits that exist solely to push a particular political agenda.
Dickens created some world-class villains. Bill Sikes (Oliver Twist), Uriah Heep (David Copperfield), Mr Tulkinghorn (Bleak House), and Ralph Nickleby and Wackford Squeers (Nicholas Nickleby) come to mind. I think “evil asshole” as a descriptor fits any or all of these characters quite well.