Grade System Snark

"Okay, so I'd give us an A for effort, a B for skill, and an..." (winces as I-beams collapse) "F... for stealth."

—Michelangelo , TMNT (2007)

When going through Hero's Journey, the protagonist will typically have to undergo some trial (or test, whether physical or written) to prove his or her own worth. The test will come at any given time, normally during the Road of Trials for the inexperienced adventurer, but for the returning victor, it can happen as early as Crossing The First Threshold. The standard obstacle (but not always) that he or she will face will be some unknown Eldritch Abomination, so powerful that it will even terrify the Mentor, prompting the fledgling savior to Take a Third Option, one that his or her mentor would never have thought have in a million years. After the fight, the mentor, still having a sense of awe and pride in his voice, will try to keep a sense of authority by making some rather snarky comments, almost as if he was grading a test, about how he would've handled the situation differently.

More than often will result in some form of Mad Libs Catchphrase if it happens on more than one occasion. Can appear as Casual Danger Dialogue also, though the timing of the quip and subsequent action can follow each other in any random order, as seen by the page-topping quote.

An obvious Sub-Trope of Deadpan Snarker. Compare On a Scale From One To Ten, which uses this ratings system with numbers instead of an alphabetical rank. Please no Truth in Television examples, as no group of friends ever seem to be able to take a rating system seriously. Contrast "The Reason You Suck" Speech, which, unlike this, there is (usually) no humor involved in the berating involved.

Examples of Grade System Snark include:

Anime and Manga

Baka to Test to Shoukanjuu: Although there is no physical test in the beginning of the series, we can clearly see that there was someone who was extremely snarky when coming up with the entrance exams: Those who scored the highest got the most luxurious classrooms. Those who failed miserably got rooms furnished with cardboard boxes.

Film

The 2007 TMNT film provides us with the page quote from Michelangelo after the Five-Man Band, directly disobeying Splinter's orders, pass through The Return and Crossing The Return Threshold phases by randomly attacking monsters (just because they looked suspicious) on an unfinished skyscraper. Needles to say, Splinter was pissed when he found out what happened.

Literature

The grades for the OWL and NEWT exams from Harry Potter. Among other things, the worst note is T for "Troll".
In the Batman short story "Cave Dwellers", which sheds some light on one of Batgirl's numerous training missions with the famous Caped Crusaders, Batman himself gives a rather nasty inversion of this, without any form of sarcasm whatsoever:

Batman: I wouldn't grade you as high as my partner.
Batgirl: Yeah? Well, I have a few words for you, too.
Batman: I don't think you passed.
Batgirl: I survived, didn't I?
Batman: That's not enough. You used lethal force against your last opponents. We don't do that. We don't kill even to defend ourselves.
Batgirl: Was I supposed to let your paperdolls shoot me? What would that have proved?
Batman: Only that you could be one of us.

From The Hitchhiker's Guide to the Galaxy: "'Ten out of ten' for style, but 'Minus several million' for good thinking."

Live Action Television

On Clayton Webb's first appearance in JAG, he gives a rating of Mac's beauty. When someone asks,"You go into fractions?" Webb replies, "I use the Richter Scale."
The Australian game review show Good Game's review of Robot Unicorn Attack: Despite giving deadly serious scores out of ten on every other game, Hex gave it a rating of 8971 Rubber Chickens. Bajo was "...not sure how to score it after that."
- In the end show summary, it have Bajo's score as a picture of a purple unicorn head.

Videogames

GLaDOS, of Portal fame, does this rather stealthily through a Bait and Switch technique. While at first she seems like she's congratulating you for a job well done after each and every test chamber, listen closely—the compliments are heavily drenched with sarcasm.
- Taken Up to Eleven in the sequel.

GLaDOS: Oh you did VERY well. I'm going to write that on your form. Oh there's lots of room here. "Did well... enough."

There's a minor report card gag in the third case in the third Ace Attorney game. The characters note things like "gets into trouble being the center of attention" supposedly getting written on others' report cards.

Western Animation

From Futurama: In "Mars University", Fry, Amy, and Gunter, a chimp whose intelligence was enhanced through a bowler hat powered by sun spots participate in a class on 20th century history. Not only is the professor in charge of the class thick on the sarcasm, but every seat in his lecture hall is rigged to electrocute any student who makes a snide remark, calls out of turn, or answers incorrectly.
Hercules: After Hercules defeated the River Guardian, sending him flying, and rescues Meg, Philotetes comments underneath his breath: "Not what would I have done, but okay..."
In My Little Pony Friendship Is Magic, this is Rainbow Dash's response to a tortoise who joined the competition to see who would be her pet; she gave him an A for effort, and would give him a gold star if she had one.