The absolute worst is someone that tries to brand themselves as a 10x engineer by constantly using programming terms like "dynamic programming", "polymorphism", "recursion" and the like, but they're really a 0.1x engineer because they don't truly understand what any of those are and when they should actually be using them, and so try to shoehorn them in when they don't need them while also not understanding them, and end up writing low-quality crap.
Took too long for management to get rid of that guy.
All my experience in trying to hire developers has been wading through an endless stream of people who were just useless.
Me: I want to represent a 2d grid, what data structure should we use? Them: A string?
This was someone applying for senior engineer. Others I've had filled their CV with SQL related acronyms. But couldn't explain what a foreign key was and then stubbornly insisted that at their current corp they would never ever use foreign keys in their SQL database!
I've had senior engineer when asked how to check if we had a 2d array with an item at x,y tell me if anything is on the same column or row, they couldn't do it, couldn't even verbalise how to approach it.
"Web Developers" who didn't know the difference between GET and POST. Web Developers that have never heard of PUT or what it would be used for.
The answer that almost guarantees I'll hire you is "there's got to be a library function for that, so I look in the manual". Almost as good is somebody whiteboarding how they'd convert ddd to mm-dd (and then account for leap years, etc.)
I get a disturbing number of people who say things like "I would communicate with the person asking for this to see what they're really intending blah blah"
My favorite answer was on a phone interview where he just hung up and wouldn't answer when we called back.
Someone who produces absolutely nothing and have no impact has cost, but is still better than someone who produces net negative. And the people who solely act as interface between LLM and whatever might fall to later category.