Well since this thread has already gone off the rails, I will just add my recent experience to validate this. I went into the dealer for 10,000 mile service just to keep them happy in case I have any warranty claims down the line. The next day I am driving home and start smelling oil. I figure they probably overfilled or something. I get home and open the hood and the cap is sitting in the front of the engine bay and oil is splattered all over the place. Idiot forgot to put the cap on after filling it. How do you manage to fuck up an oil change?
Had the exact thing happen on my Nissan Altima 3.5 twice. One time they left the dip stick out. It was sandwiched between the engine cover and the hood blanket. This change was done in the winter. About a week after the change, I got stuck in some snow, so was rocking the car and getting on the gas a little and could smell burning oil. Because I was on the gas, the oil was blowing out of the dipstick tube all over the engine and engine blanket on the hood. The dealer cleaned the engine, but I should have insisted on a new hood blanket as I could smell oil for a long time after. Anyway, a few changes later, they left the oil fill cap off, again sandwiched between the engine cover and hood blanket. I caught this right away as after the first instance, I always took a quick look under the hood after a change.
I do as much as I can on my cars as my confidence in most dealers and shops is kind of on the low side.