When I tie scud flies, I like to weight them a bit, therefore I do not use a scud hook, which has a curved shank. Putting weight on a curved shank inverts the hook (rides upside-down) in the water which is unnatural for scuds.
Instead I use a straight-shank nymph or wet fly hook and start the body just around the bend of the hook. The scud stays upright tied that way and I can dead-drift it or add a little movement with the fly remaining right-side up.
Further, when most of us observe scuds, they are out of water in a curled up position. If you look at the videos above, with scuds in their natural environment, their bodies remain straight, with a slight curve towards the tail.
When tying flies; any flies, not just scuds, observe how they ride in the water/current when attached to your tippet. Flies that ride upside down are desirable for some species, but not for scuds, IMO.