I think an important thing that no one has mentioned (or maybe I missed seeing it) is that you also have to take into account the region / area the animal comes from.
For example: Shoot a deer that lives in the forests of NY, who eats only red acorns and grass and twigs and suburbanites' flowers, and never any wheat or corn or apples or other sweet fruits and you will be very hard pressed to have it not taste gamey.
But take that same deer, relocate it to the farmlands of Wisconsin for a few weeks, and now you've got one VERY nice tasting deer.
I'll never forget how good the doe I arrowed in Wisconsin tasted, and yet she came in running & nervous as all heck, and then she ran 100 yards after the shot before dropping, so she was full of adrenaline.
Then again, she laid out a blood trail that Stevie Wonder could follow, and some would claim that is why; she bled it all out.
BUT, all the other deer harvested that week tasted just as succulent, too, so I don't think the "bleeding out" was the reason.
I think that a big part of it is that they just are what they eat...
To kill something as great as a duck just to smell the gunpowder is a crime against nature. - Alan Liere
Democracy is a device that ensures we shall be governed no better than we deserve. - George Bernard Shaw