For red/blood... Fish don't see blood. They eat their prey whole, or if it's mangled/dead/whatever, the blood has already dispersed. They can smell it, but they don't relate a smell to a color. That simple. Now that's not to say they might not want the extra red color in it.
For legs on poppers I would stay to black or white. Anything else isn't really needed IMO as they'll probably only be seeing a silhouette of it anyway. It's a reaction strike, not something that sits in front of them while they decide to eat it or not.