The Grin of the Dark by Ramsey Campbell
Technically a spooky clown book, a premise so stale that it kept me from this title for years. What a pity! The Grin of the Dark isn't about scary clowns at all but instead anxiety.
Researcher Simon is writing a history of an old vaudeville star and as he does so his life falls apart. Is he losing his mind or is the deranged clownishness of his subject somehow taking a grip of the world around him?
The novel is an extended failure dream, Simon lurches dizzily from one absurd inconvenience to the next, one absurd set-piece of failure and humiliation after another. In this way it most resembles English comedies, imagine an extended episode of The Office but without any catharsis. We don't get a laugh track, a reassuring roll of credits, the reset at the beginning of the Looney Tunes short where Daffy Duck is restored whole and unharmed.
The reader doesn't get that out, we are allowed to recognize the cosmos as a snickering Bugs Bunny conspiring some mischief for the narrator but we aren't being winked to. We aren't in on the joke, we're the butt of it. It turns out that's scary!