I mostly read non-fiction. My ratings are usually the following:
- piece of junk, the author has no idea what he/she is doing and the book is full of error. It might even be a bad piece of propaganda. Examples are The Secret Life of Cows (Rosamund Young), which just is the author inventing stuff about how her cows think, or The Origins of the Modern World: A Global and Ecological Narrative from the Fifteenth to the Twenty-first Century (Robert Marks), which has so many factual errors that I in the end just gave up;
- it was an ok read, to the point and informative. Most of the non-fiction books I read are here. Examples are WELS & Other Lutherans (John Brug), Gateway to Malay Culture (Zapi Ragman) or Stoic Logic (Benson Mates)
- a good read. I learned a lot and it made me think. The book is well-researched and the author knows what he/she is done. Examples: Le Siècle de Louis XIV (Voltaire), which has a lot of information but bored me to tears (it doesn’t help that Voltaire is extremely biased and love facts and dates too much) or A Short History of inguistics (R. H. Robins), which is good, but cliché and never got updated.
- an excellent read. A factual book with a high level of scholarship, which made me think a lot, gave different points of view and has loads of info. The Rulers of Magindanao in Modern History (Michael O Mastura), which completely changed how I viewed colonial history of South-East Asia, Geologica (Robyn Sutchbury), which gave me a lasting love of geology, or La grammaire de Denys le Thrace (Jean Lallot), which is an excellent commentary;
- a masterpiece. An opus magnum. Examples are the The Great Church in Captivity (Steven Runciman or A History of Education in Antiquity (Henri-Irénée Marrou), a masterful take on respectively Orthodox faith after the fall of Constantinople and education in antiquity.
My average rating on goodreads 2.48 (+1000 books rated), so I’m quite picky.
In general the rating is how you like the book. Some might think that one book is excellent. Others that the same book is junk.
I usually ignore them, to be honest. It doesn’t help that I usually have no idea who the other authors are.