I write what I know, and I know the endings to most 90s movies. That means that most of what I write comes with a healthy portion of cheese. Now, you may feel some resistance when you drop a dollop of premium Havarti in the middle of your story, but I'm here to assuage those fears.
Don't fear the cheese, brah!
First, let's get on the same page. The same sheet. The same single-slice of American Gold. I should also forewarn that there will be a lot of cheese-based metaphors and puns throughout.
What is Cheesiness?
A cheesy scene might be something sweet and saccharin, like a happy ending or a joyous reunion. It's a Meet-Cute, a bit of comic relief, or an impassioned speech in a locker room. Cheesiness is an overuse of metaphors, slathering gobs of melty queso atop an already overflowing literary nacho stack. It can also be an abundance of similes, like a Caesar Salad that is 90% Parmesan slices.
Cheesy is the hero's friends coming to his aid in the 11th hour, even though they had a fight only a short while ago. Cheesy is the main love interest finally realizing their feelings, but only after the hero has left on a suicide mission. Cheesy is the adorable alien Murf-Rat getting all the best lines.
What's So Bad About Cheese?
Today, with our de-saturated colors and double scoops of grit over every comic-book movie, cheese is seen as a throwback to a bygone era. Cheese is a simple sharp cheddar, but today's audiences demand a hearty and well-aged Gouda. Cheese is happy when the story feels sad.
Some people think that cheesiness pulls the audience out of the moment. That a brief glimpse of light will spoil all this sweet darkness we've piled on for the last four chapters. They think that if Superman smiles EVEN ONCE, the whole movie will be ruined.
There is a point to this, and it's called Bathos. Coined by Alexander Pope, the term refers to a dramatic and jarring shift in tone (usually from serious to comedic). It can be seen in pretty much every movie, and there's a fine amount of YouTube devoted to the concept. The point is, Bathos is not necessarily cheese, and Cheese is certainly not always Bathos.
When Thor and the Incredible Hulk finish an amazing fight scene, only for the Hulk to exact a sudden and comedic sucker punch (a callback to an earlier fight), that's a bit of cheese. It's a serious moment, but the character is still a bit...cheesed off..about that other fight. We accept the moment and laugh along.
When characters make snarky quips too often, it removes the tension from the scene and undercuts the seriousness and drama of the movie. It's hard to level these accusations at the MCU and DCU, considering these are based around comic-books featuring literal gods battling other gods. But when you see it in CSI, or Castle, or LOST, or Star Trek, or Star Wars...eventually you lose any sense of danger. And when there is no danger, the audience is checking out.
Cheese has to have a limit. Just as the audience needs to be somewhat lactose tolerant, the author needs to be mature enough to leave some of that sweet Brie in the fridge.
So What Do I Do With All This Cheese?
First of all, I think we've passed the usefulness of the analogy at this point.
Second, don't be afraid to store scenes for later use. I have dozens of notebooks around my home, all filled with ideas and scenes and characters that simply did not fit with any of my current narratives (I have, on average, three projects rolling at any time. This isn't a brag, it's about momentum, and we'll talk about it Thursday).
If you have a great speech, but it comes across as too playful, stick that bad boy in your pocket and bring him out another day. If you have a romantic scene that's straight oozing Mozzarella, maybe it needs to go into the oven to cook a bit longer. Don't shy away from these ideas. Embrace them. But use them appropriately.
If you story has no love interest (not necessarily sexual in nature, or even strictly human-on-human), then you've done messed up. That's a quesadilla without a drop of cheese, so it's basically a tortilla chip.
If your story only has strict soldier-types barking orders and rendering salutes, then you done messed up again. You've made a grilled cheese sandwich that is just untoasted bread slathered in mustard. What is the matter with you?
If your story ends on the absolute bummerest of notes, then you done messed up a third time and you don't get to write again for a week. That's a life pretending almond-milk-based-cheese is a thing.
Don't be afraid of a little humor, sex, or relief in your stories. Embrace the cheese.