I use work for a place that did paint touch up for the Lexus dealership, normally they'd clean the cars before we got them but one time someone dropped off a car to be serviced that had (what I'm fairly positive) was a milk substance spilled in the car and left out in the heat for what I assume was an eternity because it smelled absolutely terrible
I've never been the type of person where my stomach turns over easily but I was literally driving less than a 1/4 mile and had to pull over and step out of the car because it smelled so bad