mine is olive.
are you fishing them in lakes? or rivers?
fish them near weeds and and bottom cover.
use of a indicator works well to keep it right above the vegetation and slowly twitch it every once in a while to mimic the actions of the scud.
.usually they are no deeper than 5 feet.
when the scud gets frightened it can move in fast scoots like a crayfish.
but dont waste your time scooting a scud quickly.
only on rare occasions does this work.
also if you are going to be tying them, tie them straight! not curved. curved ones are either dead or resting or feeding.
also tie some with a orange bump 3/4 of the way up the hook shank. to simulate a pregant scud. sometimes this is what the fish key in on.
also pure orange scuds are dead and sometimes the fish key in on only the orange scuds.

but everyones opinion on scud color isnt important.
they matchtheir color to the environment they live in. i use green because all of the vegetation in my locallake is green.
but if yours is tan then you need to be using tan scuds.
tie yours or buy them....lwhatever you do in sizes #20-10 and youd be set.
you also must make them have a scruffy underside to suggest the legs.

also molting scuds that do not have their exoskeleton yet, have a distinct blue/grey hue. another thing to think about.

wow sorry for the long post just though it should be informative!
hope it helps!