Can you judge a philosophy book by it's cover?

A philosophy book with a simple exterior, is typically more dense internally. Id est, it takes a little more thought to get through.

On the other hand, a philosophy book that has a more colourful, or designed, exterior, is typically for a larger audience.

What comes to mind for proof is the Cambridge and Oxford books I have of the writings of Schopenhauer, versus some of the I Ching or introductory philosophy books I own.

For the most part, I think this stands fairly true.

Thoughts on this conclusion?