Why would you add water/salt or anything else to blood?
When a deer is shot, and runs off wounded, it bleeds. It bleeds in a manner dictated by where it was shot and what was damaged, and that blood will be spread depending on how it is then moving. All we can replicate is the type of material left behind as it runs off, and we do that by taking blood (including clots) from an animal that has just been shot. If clots are present inside the cavity then surely it is feasible that there will be clots left behind by the deer as they exit from the wound. A lump of blood clot will I would imagine give off a very strong smell to the dog, interspersed with tiny spots along the proceeding and following route that the deer takes.
So, that is a long roundabout way of saying that use deer clots along the track, see if the dog indicates them to you or shows more interest in them. It is all part of teaching the dog to tell you he has found something.
from what I have been taught and learned I would always use deer blood (or boar) because that is simply what comes from the animals I want a dog to follow and to ignore all other scent along the route.
I agree with deer man in that respect, deer blood to be associated with deer only (although I don't think that is quite what he is driving at), but as for making things too easy??? That is why I was suggesting a couple of hundred ml over several hundred metres, not a bucket poured out along the route.
More importantly though, the dog being trained should certainly be given tracks easy enough for him to succeed at in the beginning...