If you want to be really evil, you use Thioacetone: https://blogs.sciencemag.org/pipeline/archives/2009/06/11/th...

As far as I'm aware, it's the worst smelling chemical known to humans and has no damaging long term effects. You just have to be veeery careful about it unless you want to stink up the whole town by accident.

This reads like an urban legend. I’ll have to shake the rust off my OChem lab experience and try some synthesis.

Kidding of course, but I it makes wonder how easy this would be for an amateur to synthesize. The consequences being making an entire town nauseous makes this whole thing pretty enigmatic.

I think if this was sprayed into the insides of your car, you'd probably never use the car again and/or never steal packages again either. The trauma resulting from the smell might just be enough.

Having once had a package thief open/dump packages in my back yard, next to the house, I would prefer you don't do that.

The packages were some rolls of vinyl, a box of sealed granola snacks, and some inexpensive jewelry, all rejected by the thief. If the person was homeless, I'm surprised they ditched the food, it was nutritious and shelf-stable. (I redelivered the packages.)

Some part of me is prepared to pay that price.