I was let go once because I gave my 2 weeks notice, and they "accepted my resignation early" and walked me out the door. I honestly can't believe the treatment I had to put up with there.
Job started out great, but slowly I noticed an inexorable trend of my career into the toilet. I had an entitled, but promising young employee that began throwing hysterical fits. As her manager, It started when I got her the best reviews, bonus and raise for the entire division for her level but it wasn't high enough for her and she got angry at my personally. She pulled all kinds of stunts and I was given the choice to fire or or try and work with her. In hindsight, I chose incorrectly and decided to be a good manager and do the 'correct thing' to work with her instead of fire her. I should have fired her. Fast forward a few months, and my managers inexplicably began to take her side in every discussion and dispute and started to have complete blinders on when it came to my performance. My accomplishments were largely ignored or depreciated and every criticism documented and lengthily reviewed. I was forced to redo my annual employee evaluation of this young employee 6 times because she 'didn't like it' and my manager made me go back to the drawing board. It got to the point where they were writing the responses, I was delivering their words under their direct guidance, she was getting mad at me for what they wrote, and the managers then turn on me for delivering another unacceptable review. She must have been blackmailing them or something. Such a waste of time.
As things began to sour, I even got disciplined once for calling a former employee on company time to ask for advice on how to survive. My access was restricted, my privileges were revoked, but the worst was people who were telling me they were doing things for my own good were by far the most critical and non-supportive. They said trust me, so i did, and they used that trust to convince me what a terrible employee I was and that I needed to be humble and accept it. When I pointed out the good things I had done, the typical response was "yeah but..." I got burned out trying to convince them I was a good employee and a smart individual and failed in convincing them of something they'd already decided. I'm not perfect, I made plenty of mistakes, and it was clearly not a fit but...wow. they chewed me up and spit me out.
It took years to recover my confidence and overcome the psychological stress those people caused. I now hate annual reviews with the burning passion of 1000 suns. I've also never seen a company do to a manager what those people did to me.