A black and white crankbait does not necessarily represent shad, it is however the maximum contrast color combination in poor light conditions, like night. What you may have experienced was a hot reaction bite and you may not have tried other high contrasting colors. Chartruse and brown are both in hot color range, brown is close to red and chatruse is close to yellow/green. Think of primary colors; red, yellow and blue, everything is a mix of those colors. Chartruse/brown can be a crawdad color in off color water or a sunfish color. Shad colors are silver with purple/chartruse, therefor black/white maybe closer to a shad, under poor light. Blue/chartruse may have been the ticket if sunfish were the prey or silver/purple for shad, only the bass knew and you had a couple of very good days on the water.