Sometimes when I look at a manuscript, I find it suffers from what I call first-order approximation plots. They aren't bad plots exactly, but they're plots that have either stalled out without resolving or they're too well worn. The language can be beautiful and the words can flow, but in the end, if the plot isn't working, a the result is an unsalable manuscript. Here's a list of what I see most of.
Wish Fulfillment Daydreams - There's absolutely nothing wrong about imagining nice things happening to nice people, except it makes for a flat plot. (Yes, I want a star cruiser and cool magic powers, too.) In most short stories, conflict and the reaction to conflict reveals character, and most wish fulfillment manuscripts have very little (or easily overcome) conflict. This type of plot frequently suffers from a passive telling of events instead of an active unfolding of action. Not to be confused with the The Revenge Fantasy.
Driving To The Plot - A big flag word in this type of manuscript is the word "decided," as in "He decided he would go to the store." ...And then the manuscript spends three or five paragraphs describing the trip from point A to the store. Getting to the store may seem like a character's problem, but it isn't. Another flag word is "wondered," as in "She wondered what it would be like to walk on Mars," followed by supposition or a wish fulfillment daydream. The problem with Driving to the Plot is that the reader has to wade through three, five, or more pages of exposition, back-story or description before we learn what the character wants, or a precipitating event threatens something the main character loves. Get us there sooner. Get her on Mars!
Satire - There's confusion about what satire is. It's not simply making fun of something. It's not even being sarcastic about mainstream society (the aim of sarcasm is to hurt someone or something). Satire aims at fixing a wrong by taking a person's, institution's or society's quality or qualities, magnifying them until they're way over the top, and then writing about them. I think sometimes authors are worried that they're going to offend somebody, and wind up calling a manuscript "satire" as a defense. Or they are being sarcastic. In any case, they shouldn't have to call it anything and let the humor and social commentary speak for the piece.
The Angry Young Man Manuscript - Pick a cause, or make one up. Now have your characters act at low capacity but nevertheless achieve the cause's goals just before dying, or fail miserably in a very un-cheery way just before dying. I'm trying to imagine Ursula K LeGuin writing an Angry Young Man Manuscript, and the closest work I can think of is The Word For World is Forrest. If you must write an Angry Young Man Manuscript (and I know you must), try to make it as layered as Ms. LeGuin's.
My Characters Are All Capitalized Stereotypes - "The Business Man stood over The Crone and smiled a wicked smile. But before he could evict her, The Child rode in on A Big White Horse with a bag of gold." Okay; I haven't read something this vague in a very long while -- yes, it may be clear in the author's head what The Business Man looks and sounds like, but all I know is that he's a male character somehow connected with a business of some sort. The problem may be that the author is trying to be ageless and dramatic. Or maybe they're relying too much on Jung's collective unconscious. The cure is to remember two things: 1) specific details are your friends and 2) give your characters names as well as descriptions.
This isn't an exhaustive list - for that you can get lost at Television Tropes or at the Turkey City Lexicon - but it's what I see the most of.