These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Jonathan Creek
Angst? What Angst?: In "The Grinning Man", Joey nearly drowns after falling into a tank filled with the corpses of people that have vanished over 70 years, coming face to face with her dead friend who was the last victim, in a scene that has earned an impassioned entry under Nightmare Fuel on this very Wiki. By the next scene she has completely recovered her composure, and at the end of the episode is looking forward to writing it up in her blog.
Big Lipped Alligator Moment: In "The Seer of the Sands", Carla's husband casually mentions that he was once married to a man. Carla understandably freaks out, but after the episode in question, it's never brought up again.
Also, in the episode "Danse Macabre", what was the deal with the Creepy Child who was obsessed with rotating blades? You'd think it would trigger a Eureka Moment, but...nope.
Critical Research Failure: "Murder at Gallow's Gate" has a woman identify a murderer from a line-up of suspects...whilst in the same room with them. She's actually escorted past them, giving the would-be killer ample opportunity for a good look at the key witness.
Crosses the Line Twice: Carla Borrego's crime show Eyes and Ears, which sensationalized various murders in order to get high ratings. Jonathan's face in "The Chequered Box" is fairly priceless when he witness actors restage a hypothetical murder in which the female victim is punched in the face and strung up with a noose.
Fridge Horror: In the second episode of the first series, "Jack in the Box," Maddy describes Alan Rokesmith's eyes and retrospectively recognizes the "hollow calm" of a man who intends to commit suicide in poetic, almost flowery terms. By the time the second series rolls around, we find out she likely recognized the same look in her mother's eyes prior to her own suicide when Maddy was just 17.
Hilarious in Hindsight: After exposing a murderous inspector on air, Jonathan is shocked to find out Eyes and Ears wants him to do 26 more episodes on impossible crimes. Jonathan Creek ran for 27 episodes.
Jumping the Shark: Lots of people consider Series 3 and 4 this— or if they don't, even many more sympathetic viewers think 'The Grinning Man' was this.
"The Clue of the Savant's Thumb". A very convincing prank lead to government assassins murdering anyone involved in the "intelligence leak", while Jonathan's new wife convinced him to quit magic, move out of the windmill, become a businessman in her family's company... and hang up his duffle coat for a suit!
Narm: The infamous "flying cat" in The Judas Tree. The script calls for a cat to jump onto a picnic table, but to avoid any tedious waiting for the cat to jump up by its own volition, somebody simply stands off-screen and throws the cat onto the table-top. The trajectory is all wrong, and it results in a scene in which the cat is clearly not jumping up from from the ground but from mid-air, giving the impression that it's just flown in.
Narrowed It Down to the Guy I Recognize: Mostly averted, with the best-known guest stars more often playing victims or cops. A few exceptions: Jay Benedict in "Satan's Chimney"; Maureen Lipman in "The Tailor's Dummy"; Celia Imrie in "Gorgons Wood"; Paul McGann in "The Judas Tree".
Replacement Scrappy: Surprisingly averted after Maddy left the show. Although she is far and away the most popular sidekick, both Carla and Joey were generally accepted by audiences.
Retroactive Recognition: Fair warning—if you watch QI before you watch Jonathan Creek, you may find it difficult to take Alan Davies seriously.
Seasonal Rot: A lot of people felt the 2014 series didn't live up to previous seasons.
Tear Jerker: Barry's recounting Maddy's childhood for Jonathan and Jonathan joining her at Gordon Hill in "The Scented Room."
In the same episode, we have Maddy's admission that she might have "stepped in front" of the wreckers knocking down her childhood home if Jonathan hadn't arrived when he did.
Trapped by Mountain Lions: In The Clue of the Savant's Thumb, Joanna Lumley's character is haunted by her past at a girl's boarding school in which one girl died in her bed and was found with a strange circle on her forehead. The entire subplot has nothing whatsoever to do with the rest of the episode, and isn't really a mystery considering the character knew the true circumstances of the death all along.