You want to ask beforehand what they are exactly going to do/change.

Oil and filter is a given but whether you get air/pollen/fuel and new plugs is what you need to find out.

A good tell tale sign that the car has been to a Ford dealer is that the front tyres will be bald, there will be less fuel than when you dropped it off and about 50 extra miles on the clock.
You could also find bacon/sausage fat on the passenger seat if your car was lucky enough to be chosen for the "sarnie run" and if you're really lucky you may get a couple of kerbed alloys, swirl marks in your paint from the courtesy sanding down with the sponge that the chav just washed Mr Hussain's Tranny with and greasy hand marks all over your gearknob and steering wheel.

Oh and you'll be considerably lighter in the wallet dept.