I agree with reb.... I believe the most important thing is how the deer is handled when killed. Hopefully, a quick , clean shot, ( no running and chasing), that bleeds the deer out well, and it should be field dressed as quickly as possible, washed out , and cooled down. I've had good results whether I've butchered immediately or let them hang. I think it is easier to butcher if they hang at least a day, so that is usually what I try to do. Also, I filet everything, and I am probably pickier than most when it comes to removing all fat, and trimming. Most people probably don't want to take the time, and hurry the job up. If you take care doing this, your ground will taste much better. I can tell what the outcome will be by just looking at someone's ground meat...if there is a lot of deer fat ground up in the meat, it will be gamey..so the more white I see in it...the less I want to eat it. I usually cut the loins into steaks, and sometimes the hams, but also like to make roasts from the hams. I can trim out 3 distinct roasts from each ham that have no fat/sinue. All the rest I grind up usually. Once in awhile I will make a roast from the shoulder/neck area.
Also, I believe you have to be careful not to overcook deer. After being "picky" in my processing efforts, the result is that my wife and kids prefer deer over beef. If you use the ground meat in soups, it is so lean that when you look at your soup in the fridge the next day, there is no fat floating on top.
My daughter visited us from another state recently, and when she flew back home, she packed up some frozen deer in a cooler and took home with her. When she got back to her home, she cooked some for a friend, and he said, "man, I gotta get out and start hunting !"
Thats my 2 cents worth.