The most likely cause I believe, is gut shot or poorly gutted animals. We should always wash out the body cavity of our game as soon as we can, I believe this is the first step in producing quality wild table fare.
I have to agree with Lil John since it has been my only experience with poor tasting meat. My father had an incident with a "gut shot" on a doe where he and the group of guys he was hunting with pushed the deer for 6 hours before they found the doe leaning against a tree where they delivered the fatal shot. That was the worst meat I ever tasted. So bad that my father didn't hunt deer for the following two years. Other instances that I know of people making a less than desirable shot didn't turn out so bad when they allowed adequate time for the deer lay down and expend itself. I would speculate that the adrenaline in a wounded deer that is pushed causes the poor tasting meat.
Another cause is not getting the meat cold enough quick enough. Maine is a state where it is traditional to let a deer hang for a day or three. That can't be good, especially outside where the flys can get at it.
I have heard it said that a deer shot and left to run a while toughens the meat.
Lil John, you are right. An unwashed body cavity and many folks not knowing the proper way to field dress an animal can really foul up some meat.
If you guys have your own methods that seem to work well we could start a new thread and post them. I know when deer season rolls around there are people looking online all the time to find out how to properly field dress a deer.
Hey Steve! Somewhere recently, I saw a new tool to help in field dressing deer. Something along the lines of the "rectal router". Insert it to the stop, turn it twice, remove.
This is the toughest part to get right when field dressing so the tool makes sense!
Now if I can remember where I saw it. . .