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.
Big Lipped Alligator Moment: Most of the things you find in the dungeons are standard fare, among which are traps like bombs and boulders. However, one rare trap ends up throwing giant spinning fish across the screen.
This is also pretty good for dealing with pursuing foes like those angry roper things if you're lucky. Best works with Charme who can detect traps without a ring.
Recette's Father when you find him. It doesn't matter what you were expecting to see, chances are it's not that.
Breather Boss: The Gauntlet "boss" level two-thirds of the way through the Obsidian Tower, which is packed with a pretty large and exhausting variety of monsters, particularly various varieties of slime. Much, much easier than the other bosses at that end of the game.
Demonic Spiders: Ropers initially thanks to a bug. They hit you once and you are either left in single digit HP or dead.
Regular enemies which usually deal pitiful amounts of damage in earlier dungeons become this in The Crystal Nightmare, where they deal larger amounts of damage, and get tougher with every floor you clear.
So insanely high she can save your butt on Survival, especially on 1.106. Get her to buy a rug or ask for 'something metal' and you'll get near half a million pix off her in one sale!
"Funny Aneurysm" Moment: Tear is quite pleased when Caillou thinks she's the proprietor. Given what we later learn about the treatment of fairies, she's probably not used to getting that kind of respect. Caillou himself thinks it's unexpected, though he's more willing to believe a fairy is in charge than a girl his age.
Game Breaker: In 1.105 and 1.106 at least you can sell vending machines in vending machines. Physics aside, this can be a very good way to make money fast once you have the capital to get it started.
Considering Tear says point-blank you (supposedly) can't resell vending machines, this is almost certainly a bug.
Also works wonders during a metal rush. Clear out all but the showcase of metal items. After those get sold people will ask you to 'sell them something metal.' Pick the most expensive vending machine and jack the price.
Little girls seem like this if they're treated as every other customer. However, when treated as an investment, they become a welcome sight at all times.
Euria, who will constantly try to sell you Treasures, which most generally are useless commodity you can obtain, at ridiculous prices (300~350%), more or less insuring the destruction of your combo. note She IS a good source of rar-ish treasures needed for fusion. The most annoying thing is when she tries to sell you utterly common rugs for a million pix, or gets stuck in a thankful statue/gold statue loop (both of which can be bought in the market shop). Made worse by the fact that if you actually buy something from her, she'll show up more often.
Prime will only pay base price until you increase your relationship level with her, the fact she tends to pick up the most expensive items in your display case doesn't help either.
Lightning Bugs. They're very small flying enemies, move faster than you can, and slow you when they hit. When you first encounter them with Louie (a melee character), you will be frustrated.
Gnolls can also be very annoying at first. While their ranged attacks can be blocked by Louie, they have some fast melee-range attacks for when you get closer, and the block only works if you face them and aren't attacking something else.
At first, Bombs are these. When you kill one, their corpses become bombs that can cause massive damage, so knocking one down in tight spaces without losing much health could be hard. Being sufficiently armored though minimalizes that.
Statues are very annoying, especially in groups when they can obstruct your adventurer from going further or close enough to attack them.
Good Bad Bugs: Thanks to Gameplay Ally Immortality, Recette is completely immune from damage while in the dungeons. On rare occasions, the floating pumpkins will attempt to land on her. If your adventurer is far enough away, you can completely avoid damage, and close in to attack them, while Recette remains completely unharmed.
A Running Gag is Recette A) concluding that Griff is in love with Tear (much to Griff's consternation) and B) declaring her intention to stand in their way: "Too bad, because Tear is my -"
Most Annoying Sound: Recette's voice, mostly due to the nature of Japanese's cute girl type dubbing, especially that she loves to say "Daijoubu? (You okay?)" in nervous tone almost every time an adventurer gets hit in a dungeon.
Moe: An impressively large portion of the cast has the Moe look. Recette especially fits the archetype; one reviewer described her as "cute enough to induce insulin shock." Even somewhat lampshaded in the dialogue: "That girl: something about her inspires people to care." One wonders if the Japanese version of that line included the word "moe."
Griff, Rebel with a Cause in the Obisidian Tower. He can down an unprepared adventurer with two attacks. He is also swift, difficult to counter and loves to spam magics all over the place.
The Geddon Device, the Final Boss (or Bonus Boss since you can only fight it in Endless Mode), in Lapis Ruins. It has a wide array of attacks that are either extremely damaging or difficult to dodge. It is well known to downright one-shot poorly equipped adventurers.
The Scrappy/Scrappy Mechanic: Elan, especially early on. If you plan on selling anything to him, you WILL be taking a loss of profit, since he seemingly never carries any more than 1000 or so pix on him whenever he visits your store, no matter what the reason (though he does start carrying more as you start to raise relations with him). In the dungeons, he initially seems useless with fast but terribly short-range attacks, terrible SP and no defensive skills (though later he's faster than average, as his rage skill plus healing rings turn his massive HP more massive and his damage output similarly massive).
Euria exists only to force you to spend ridiculous amounts of money not screw up your Pin combos. People have actually gone so far as to avoid all cutscenes during the times of day that she could appear and thus start appearing in the shop.
She's helpful until you have all rank 5's unlocked. You should definitely avoid her cutscenes after you have Elan's friendship note thing and all fusions unlocked and sold to your adventurers, however.
You don't need to avoid her cutscenes. Just decorate the store so that she avoids it.
Your customers will often sell you food... with a quote about how it's a "family heirloom" or "my grandfather used it with love before he passed". Now honestly, when in any J/RPG you've ever played - or even any video game - has food actually spoiled with age? Fridge Brilliance without the fridge.
The Woobie: Recette, if you believe the Fridge Horror that she's probably been starved for a while before Tear comes to help.
Woolseyism: Carpe Fulgur's localization is top notch, capturing the game's humor and charm perfectly while sprinkling in numerous clever references to other relevant works and maintaining a biting sense of humor. Of course, this trope shouldn't be a surprise when Andrew Dice, one of the two founders of the company, even lists Ted Woolsey as an influence.
For a more direct example of this, the game's memetic catchphrase, "Capitalism, ho!" was eventually admitted to have come up as a whim of the writer, having no equivilant in the Japanese script. He commented in the translator's notes that given the popularity of the phrase and its effect on the game's marketing, he wasn't too concerned.