But if they were off by themselves would they chase a deer if they found the scent?
Most likely. Once they know you want them to follow it, they usually want to. Deer are easy for them to follow and dogs have a natural attraction to them. I doubt I'd train a hunting dog to track deer. The ones we use are always working dogs that hang around the farm or yard and do not have the instinct to be constantly trailing something. They are easier to control and we don't have to worry about them trailing off-game when we take them hunting.