This thread is finally getting good.

Workshop Mb nailed it, and also someone mentioned that they had a tech do spark plugs on their Ml-320.

If you were caught taking out spark plugs at either dealership i worked at with an air wratchet and you got caught, the shop foreman would personally stuff your air wratchet where the sun don't shine and send you packing, and that's after they ambarassed you in front of the whole shop with the loudest verbal belittling you could ever imagine.

I would not take my mercedes back to that shop ,nor would I ever dream of taking spark plugs out with an air wratchet unless I wanted to see what the threads looked like in a ruined cyllinder head.

yeah, when you are mobile like me and worshop mb, you cannot make mistakes or cut corners or do shoddy work.
Wheel bolts must be torqued before and after test driving the vehicle if the wheels were off, you actually get better quality work that way than just taking it to the local shop and leeting whoever gets it work on it.
Remember, you can always request a certain tech at your dealership, and if they turn you down, go somewhere else.

As far as that guy taking spark plugs out with an air wrench, I would just have to question that shop in general, there is no way that should fly.

Man, when it comes to spark plugs, you should only use hand tools and work slow to avoid taking out the threads with the plugs.

I wonder if that guy uses air tools on the 117 motor spark plugs.
That makes me just cringe.