Well, let me relate my experience to you, Troy.
It happened in 1995/6:
I was siting in my car, eating sushi take-away. As my car's rear
windscreen was heavily sun-shaded, a person approaching from behind
can't see if I'm inside or not.
So as I eat, I saw this decent looking chinese man in white short
sleeve shirt and black pants holding a folder-bag, walking towards
my car. I continued eating and though nothing of it because I was
parked facing the main road in the carpark outside the sport
complex. Suddenly I hear a metalic screeching sound from the back
all the way to the front as he passed by. Realization sunk in
immediately that I have been scratched.
I firstly honked loudly twice, the culprit visibly jumped ( can see
his shoulder shrugged ) but continued to walk briskly towards
crossing the road in front. I jumped out of my car and started
chasing him.
I caught him, pulled him back to where my car was, questioned him
but he refused to admit scratching my car even though I caught him
red-handed. I reported him to the Police at Clementi.
Up till today, the Police couldn't do anything about it because he
denied doing it. And guess what? This guy who scratched my car,
turns out to be the guy who slashed a professor's throat in NUS,
Raymond Ng. I still have his particulars with me, because I made
hime hand me his IC that day at the carpark.
So indeed, people who scratch cars, are likely mad 90% of the
time.
This is a true account. Not a tale of fiction.