Eeek.
I would rather have someone steal something out of my car (pssst.... the hand sanitizer is the only loose thing worth anything in there) than poop in it.
I always lock my car door. Always.
I parked my topless Fiat in front of the tavern way back when. When I came out, I noticed someone had tossed a homemade sausage on the driver's seat. I'm not sure what that was all about, but I got over it.
Leaving your car unlocked, especially in a large city, is stupid. You can't blame anyone but yourself for what happens. Too many crazies out there......