Yes, salt does attract deer.
Here is information about using salt to attract big game animals in Idaho for the purpose of baiting animals:
Hunting rules vary from state to state. Idaho hunting rules prohibit the use of bait, including salt in any form (liquid or solid) in the hunting/taking of deer/elk. Idaho does not have a regulation that allows people to use salt to attract deer and elk to an area and then "pick it up" a certain number of days before hunting in the same area. If there is still residue at the site of bait (salt) that was placed to attract deer/elk, Idaho rules prohibit you from hunting over the baited site. If the site is free of the bait, you can hunt over the site.
Some other states have rules that allows hunting over sites if bait is removed at least 30 days earlier, but Idaho is NOT one of them.