Keep an eye on your tools. The people hanging around the yards are not the most trustworthy individuals.
Amazing how many people come to PNP w/o any tools, and want to borrow yours.
And when you leave the car you were working on, double check to see if you picked up all your tools.
I have absent mindedly left tools in the past.

And have found tools from others now and then.
usually not the best quality though.
Charlie