I kinda go to the extreme...I don't leave anything of real value in my truck, because I never lock the doors.
My father taught myself and my two brothers to never lock your vehicle doors because it only keeps an "honest" man out and if you lock them, the crook will just bust out your window to gain entry.
It's been proven that crooks will always try the door latch first, to see if it's open, to keep the noise level to a minimum.
If they bash your window out, then not only do you gotta replace the stuff stolen, you gotta buy a new glass as well.
As for the window stickers? This is the only one I have proudly on display...
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I've got that beat.