<<Pacfan , I was told to do this while going to NADC and by a Ford tech myself >>
And you've stated you basically don't think much of dealership techs, so I guess this advice wasn't very good by your standards.
I've been in or around the automotive service business for my whole life, and I've never heard of anyone coating their wires with dielectric grease. That includes the INSTRUCTORS at FORD training schools, who are engineers that design the stuff to start with.
If you start with a good set of wires, the grease doesn't make them last any longer. By the time the wires reach the point where they start to break down, the grease will have long since dried up and ceased to be any help with arcing. It certainly won't hurt anything, but won't really help much, either.
And yes, there are some bad dealership techs as there are bad techs of all kinds everywhere, but overall, you're more likely to find the most competent techs at a dealership. Maybe not a very small dealer out in the boonies, but at most dealerships. That's not to say there aren't good techs at independent shops, but your odds are much better of finding one at a dealership. Anyone with much experience in the business knows this.