Rationale

That scratching?  A poltergeist behind the skirting?

Don’t be silly, that’s just a branch of the tree outside, scraping the window.

That waft of scent?  A malodourous revenant?

Don’t be silly, that’s just the bin—needs emptying.

That knocking?  Footsteps in the next room?

Don’t be silly, that’s just the plumbing—a pipe heating up.

That breath of air?  A passing presence?

Don’t be silly, that’s just a draught from the door.

That tiny movement in the corner?  The hem of an emerging apparition?

Don’t be silly, that’s … omigod, it’s a cockroach!  Help!  Help!