It's reasonable to judge a book by its cover.

[NorthernWind]

Imagine if these book's covers were without the words. Just by looking at these covers and manner in which these books are decorated it's possible to judge their content.

It's possible to distinguish between serious books and cheap entertainment just by looking at these covers alone.

You probably wouldn't buy a book about Inquisition with such a cover

or about ancient philosophy with such cover

Of course, some covers are 'neutral' but in general it's possible to judge a content of a book just by looking at it's cover.

 

[Nate Higgers]

Not necessarily, old books can get pretty bad book covers when new editions are printed out
For example: classics like Dune and ASOIAF have pretty bad book covers in the latest editions

 

[NorthernWind]

Not necessarily, old books can get pretty bad book covers when new editions are printed out
For example: classics like Dune and ASOIAF have pretty bad book covers in the latest editions

These can fall into 'neutral' category or some covers were just bland in the past.
But still if you see super cheesy and flashy cover, it's very unlikely that you will encounter history of medieval theology or quantum mechanics under such a cover.

 

[NorthernWind]

Not necessarily, old books can get pretty bad book covers when new editions are printed out
For example: classics like Dune and ASOIAF have pretty bad book covers in the latest editions

Btw, I probably never saw classic books with a truly trashy cover.