Mystery Net Community Writing Mysteries

Clues and they way they are "dropped" into mysteries can intrigue a reader, confound them, confuse them or challenge them. The lack of clues can anger a reader. It is no fun to have a twist or solution dropped on you at the end of a book or story with no prior indication. Do you believe the reader deserves some valid clues to solve the mystery, even if it was a very subtle clue buried in prose at the beginning of the book?

Do you get angry when a surprise ending comes "out of the blue?"