Does shoving a potato in the muffler turn it black?

Soot is black. There is soot inside the exhaust pipe. Fumes are colorless.

That's a great way to ruin your motor Dufus.

Yes, the potato will then be eligible to receive reparations under Biden's plan to permanently buy the black vote for the Democrat party.

Shove a big one as far up in there as you can.  Start the car and floor the throttle pedal.   In high school, I watched a muffler come apart when this was done.  The car belonged to his father....    

One way to know for sure...try it on your own vehicle.

Why does your car burn so much oil. That's the real question