The Exorcist/YMMV

The Exorcist

 * Adaptation Displacement: Not many people are aware that there was a novel first.
 * Adult Fear: Look at it from a parent's point of view. Your daughter is ill, there's nothing you can do about it and no doctors or medicine can help her.
 * Awesome Music: The perennially-creepy Tubular Bells.
 * Complete Monster: Pazuzu, of course.
 * Contractual Purity: The inverse happened to Linda Blair when she tried to break into romantic comedies.
 * HSQ: Pretty much Karras' reaction when he finds Regan to be genuinely possessed is this trope.
 * Hype Aversion: The cover art declares it to be "The Scariest Movie Ever Made." That can definitely turn people away or lead to disappointed viewers.
 * Moral Event Horizon: If Pazuzu's possesion of Regan wasn't bad enough, when he
 * Memetic Mutation: Ever saw a screamer? If yes, there's a 99% chance demon-possessed Regan jumped in your face at least once.
 * Or an image of Captain Howdy.
 * Narm: Most people find it scary, but quite a few find it downright hilarious mostly due to just how over the top it gets: a good example would be the restored spider-walk scene.
 * Nausea Fuel: Most people were physically ill and fled theaters during the medical scenes, especially the spinal tap.
 * Nightmare Retardant: The Exorcist in 5 Seconds
 * Some find the effects work a bit outdated.
 * Squick

Exorcist II: The Heretic

 * Ensemble Darkhorse: According to jabootu.net, a background prop they call the "Nut O' Fun."
 * Memetic Mutation: "I will spit a leopard."
 * Narm and plenty of it.
 * Sequelitis
 * So Bad It's Good
 * Sophomore Slump

Exorcist III

 * Canon Discontinuity: In the third film, Fr. Morning disappears and reappears in the padded cell, chiefly due to the Executive Meddling described below, of adding the character post-production.
 * Misaimed Fandom: In general, this seems to be averted; most viewers tend to see the Gemini as a terrifying villain, nothing more. However, this was played very straight with one person: Real Life Serial Killer Jeffrey Dahmer. According to forensic psychiatrist, Park Dietz, Dahmer viewed the Gemini as something of a personal role model because of the power he was able to wield over his victims and captors. He also liked the character of Emperor Palpatine for the same reason.
 * Narm: It is NOT in the file! IT IS NOT!!
 * Surprisingly Improved Sequel: After the embarrassment that was Exorcist II, The Exorcist III with George C. Scott turned out to be a pretty damn good little horror movie; some think it's horribly underrated; and a few (admittedly very few) even go so far as to say that it's both better and scarier than the first movie.
 * Uncanny Valley: The animatronic grinning pianists at Grand Central during the Dream Sequence in Times Square. Deliberate for Nightmare Fuel.
 * The Woobie:

Dominion: The Prequel to The Exorcist

 * Surprisingly Improved Sequel: Some people say that it's this when compared with Exorcist 2, 3, and The Beginning.