I've caught a good amount of largemouth on the ned in water with 6" of visibility. Also have caught many smallies in rivers with even less visibility.
Obviously it'd do better in clearer waters, but it does work in lesser water conditions as well.
I see now that Googan baits now sell ned worms that have a rattle already inserted, which could help in muddy/stained water. Personally, I can't bring myself to buy Googan baits, tho.