Please remember that two of the three of my dogs are craigslist rescues, so we tolerate their idiosyncrasies, including snapping at me when I'm attempting to clip their nails. The tolerant one is also the one that I found as a puppy. He's a very sweet, gentle and loving little dog -- even though he's a wire-haired terrier mix of some kind.
I do manage to clip one or two nails at a time. Then I give them a break for a few days, sneak up on them and clip one or two more nails. I figure they've been traumatized enough, I don't need to take them to a stranger and scare them more than they already are.