Have never heard of a Dudley before. I've seen yellows with brown/pink noses but can't recall if I've seen a Dudley.
As for breed standards versus field, all I can say is I hate the AKC. That is all. :)
The reliable way to tell a true "Dudley" is to look at the eye rims. They are obviously pink, where a yellow even with winter nose will have black eyeliner.
I don't much care for the way AKC conformation Labs are going -- the hunting people call them "Pigadors". Many of them have lost the ability to hunt. That was brought home to me when I was the gunner for an AKC Working Certificate test at the National Specialty . . . lots of the conformation people brought their Labs out to see if they could get a WC on them (it looks good to puppy purchasers). I'd say about half of them had almost no drive to retrieve -- and they certainly didn't know what to do with a recently deceased mallard.