I'd Never Have Guessed

negative clauses--facts and feelings attributed to one or more characters as information or feelings they could not have known or felt at a particular moment in a story; information or feelings a character was unaware of, then proceeded to act, producing unfortunate consequences.

Laundry list:

Little did she know...
He could not have known it at the time...
He had no way of knowing...
It never occurred to her...
Unknown to him...
She never noticed...

These and others like them, along with their first cousin HIBK (Had I but known) are to be avoided because they represent an intrusive author, elbowing onto the page to bring forth information that should have come from the characters. These tropes are also straw men to be set up merely to be knocked down.

How can a character be held accountable for something she didn't know? Do we resent as an artifice the nameless protagonist of Daphne DuMaurier's Rebecca because she married a man she did not really know? Because the entire order of awareness was so well orchestrated, we identify completely with her, our suspicions growing in direct proportion to hers.

A character may have a premonition, then berate himself later on for failing to act on it? A character may judge something to be unsafe or risky and then proceed, later to express regret, but it falls just short of cheating to expect the reader to buy into information the author has withheld from the reader and not, upon discovery, feel manipulated.