It's my understanding that salt is added for weight, but some people say that it is added for the bass or other fish to taste. Personally I don't use salt because it decreases durability of the bait. If you do add salt, make sure the salt is as fine as possible. There is also something about iodized vs. non-iodized salt, but I can never remember what. One is supposed to be poisonous to fish. This is a big thing to forget I understand, but if I don't use salt then there isn't a problem. If you are using salt just for the weight aspect, I would recommend the High Density Sinking Additive. I'm sure others will agree with this part and correct me if anything I said wasn't quite right. I hope I helped.
Josh