Always mystify, torture, mislead and surprise the audience as much as possible. — Don Roff
Although I agree with the sentiment, I don’t think it is complete (Note: I was unable to locate the source of the quote to learn if Roff said more on the subject). Thus, I offer the following codicil:
Mislead and surprise, but NEVER lie to your audience. Everything must be possible within the context of the universe you have built in your story. If you lose the trust of the audience, you’ve lost them forever.