My first (no-longer-a)-friend-roommate had two, very neglected indoor pets. Between a litter box of shame and a turtle tank in desperate need of a water change, I eventually coughed from cilia from the combination of;
- Cold weather
- Poorly ventilated boiler heat
- Chronic vaping wax/smoking weed based on location
- all of that ammonia dude
It's still a good life. I reap what I can sow.
EDIT: The regret part was the roommate choice.