Quote:
Usually shooting a deer results in a whole lot of blood loss in one way or another. When you field dress them (aka gut them), you will find that out.
Think like a good bucket or so of blood in there, which is why it's important to learn to gut a deer carefully, since you cannot see your hands, and it's MIGHTY slippery in there. Gutting accomplishes moving a LOT of blood out and getting the guts and other yuck out, along with speeding cooldown.
Hanging may move some blood, but not too much. Some folks swear by hanging by the hindquarters, some by the head. I like gambrel hooks because I find it easier to cut them up.
Road hit deer edibility is more based on muscle damage. Usually one side or the other is iffy, if it's hard hit, it's usually not salvageable. Guts are a concern too - internal rupture does more yuck that blood in the meat. I like to do the step test - if I step on the ribcage and it's super squishy, it's a total loss - it took a heck of a hit. If it's solid, I'll take a chance and ask permission to take (I stop for car deer accidents and wait for the police so I may legally tag it). I don't pick up deer that I didn't see get hit (or was close by when it happened).
ETA: A stressed deer (or any critter) before death is a tough critter. Stress diminishes meat quality. The "ideal" car deer incident would involve a quick death for the deer, and minimal damage to the car. The longer they stress, the tougher the meat.