In my job, I read through a lot of movie scripts written by hopefuls and amateurs who want to get their start in the industry. Unlike what you may hear, most scripts are not awful. Most are only "meh". Not bad, but not great. The truth is, most scripts are probably worth pursuing. A clear beginning/middle/end, some decent characters, logical development, a coherent story, and you have a believable script. And honestly, "believable" is usually all you need for someone to show interest. Add in some decent humor and engaging material, and you almost guarantee people will want to pick it up. It's that easy.
The problem is, that's not what most people want to do. Most people get it in their heads that if they can cram in enough jokes, action, suspense, incredible special effects, or "zany shenanigans", then they don't need to bother with the rest. These are the bad scripts. These are the scripts that are painful to read. These are the scripts I hate having to endure.
The college/graduation/house party comedy. Thing is, everyone wants to believe they can write the next Animal House/Dazed & Confused/Superbad. It doesn't take much research, all you need to write about is young people going wild, it practically writes itself! A lot of people write these stories because they're so easy to write. The problem is they get turned down because they are so repulsive and unpleasant to read. Drunken people spouting incoherent nonsense while making poor choices with zero inhibitions played for comedic effect, it gets old fast. And I don't mean after you've read it for two or three scripts, I mean after you've read it for 2 or 3 pages. Find a purpose, find a plot, show us more than just what these people are like when they're annihilated, and get things moving.
The ultimate action script. Not as common as you might think. Thing is, most people start writing these, but never actually finish them, and thus never submit them. This is because their adrenaline usually runs out long before they reach 90-100 pages. Or if their stamina prevails and they do finish one of these, they are almost always short. Cut out the subplots, shorten the rising action, and get straight to the explosive climax. And while this doesn't always happen, it is surprisingly common how many times the main character completely obliterates every single enemy on their own without a single scratch to show for it. Give a guy a machine gun and he'll hit nothing but the surroundings, give him a pistol and he can take down an army with ease. It violates the most simple think a reader asks for, believability. Write a story, not the Michael Bay sequel to Commando.
The voyeur horror movie. Interestingly enough, most of the horror scripts I read are decent/believable. But some are just god-awful. With these, you can usually tell that someone wrote them with one thought in mind, "scare people". Except in the pursuit of this they have written something unbelievably un-scary. And they almost always make the same mistake; they write too much from the killer's perspective. They turn the opening scene from Halloween into a movie. We see everything from the killer's point of view to heighten the suspense! Except it sucks. When you're seeing everything from the psycho's point of view, there's no surprise to anything. You watch the people come at you and be killed. It's like playing a first-person-shooter against enemies that are incapable of hurting you. Everything just becomes unbearably predictable. Masked/mysterious killers should be outsiders/invaders, not protagonists.
The charismatic bank robber film. Everyone wants to think they can write a clever bank job where a small group/team can get in and get out nice and quick, avoiding all the pitfalls of security with ease. Essentially Bonnie & Clyde meets The Italian Job. Except they usually make it look so easy, it completely takes you out of it. The best don't make it look it easy, they make it look doable but hard. The bank robbery sequence that I judge all others by is the opening scene from The Town. 4 blue-collar guys in Halloween masks with guns, bleach, plastic ties, and a van. A bank robbery that covers and accounts for everything, even the things that we, the audience, aren't expecting. Fast, efficient, brutal, professional. These guys knew what they had to do, but they also knew they had to work fast. Any script that fails to acknowledge the necesarry preparation for this kind of job isn't worth pursuing in my book.
So take note of these kinds of scripts. This is the kind of stuff we turn away almost unanimously. If you want your script to have a chance, focus on the story first, and the rest second.