Taste like chicken,
I think the biggest cause for any "bad" tasting deer is poor performance by the hunter after the deer is shot. Unfortunately I don't get to shoot as much mule deer as whitetail, but I have both in the freezer right now and I would have a very difficult time determining which is which by taste.
When I was young, pickups were not common. The pickups that were around had little creature comforts, road like buck boards, were very low geared and generally were not considered hunting vehicles. Our '53 International pickup was crude by any way you wanted to measure it! Our '53 Oldsmobile 88 was very comfortable.Many hunters draped the deer they shot over a front fender of their car. The heat of the day and the heat of the engine would cause deer flavor to go south. I remember people saying that corn fed deer was best. Well the corn fed deer were next door. The prairie deer were across the state and mule deer were on the prairie, and not near the farm where I grew up. So, the corn fed deer tasted good. The grass fed deer, including mule deer tasted not so good. Carrying a deer 300 miles on the fender of the car was a much bigger factor then corn vs. grass or whitetail vs. mule deer, IMO.
I think that people have heard that corn fed deer taste best so many times from their fathers, uncles, grandfathers etc. that they have come to believe it. I do not. The deer in my freezer came from Eastern Wyoming and from the Black Hills of South Dakota and both taste great. I am confident neither tasted corn in their lifetime.
Bottom line, mule deer vs. whitetail both taste great.
