A few days ago a guy came running up to me at a gas station while his buddy was unsuccessfully trying to start a car and asked me if I had jumper cables, I did, but said no anyway. I felt a little bit like a heel. The car in the background was cranking over pretty good so a low battery probably wasn't the problem. However, if I'd wasted my time showing them how to jump a car without risking blowing up the ECU and it didn't start, I would have been compelled to diagnose further. It would have been a fuel pump gone bad or whatever and they'd be mad at me for breaking their fuel pump, so I didn't feel so bad then.