Vets are just like any other professional - some excellent, some bad and many in the middle.
Vets are medical doctors, just like our own doctors. When we need medical care, we go to them. When we need emotional help we go to a professional in that field and if we need help with our diet, we see a nutrionist, not a surgeon.
I've never seen Pedigree for sale in any vet clinic. What I do see is Science Diet and Iams and that is what most vets sell their clients, if the clients ask about food. Personally, I do the research myself and although I trust my vet completely in medical issues, I would never ask what food to feed my dog as she would suggest what is on sale on her shelves.