I know quite a bit of shit jobs on my country, however I know 3 that I would never ever touch, NEVER.
These are the following, feel free to disagree:
-Emergency Room Medic, always stressful, always rushing, always unexpected shit, if you fuck up someone dies, you can't be lax at all, none of these bling life that the medical investigators have, none says thanks and you only see people in the worse day of their life.
-The people that cleans corpses and shit from Crime Scenes, you have irregular as fuck work hours and you have clean and watch the worst of the human nature on daily basis for regular pay.
-Being the janitor on the Area 51 or in any Mega TOP Secret Facility that guards an extreme secret. Think about it, you will never ever get a better job since it's better for the higher ups if only a single person cleans that place all their life instead of many every few years, for the same reason you will be ascended or have salary raises, you can't also back off from it since you will know too much, also you would not be able to tell any of those secrets to anyone, if they have in some shitty box Excalibur, the map to the Golden City or some 2D Portal, you cannot tell anyone, and probably co workers are also anti social fucks since they need to be silent always too.