Venison confounds me somewhat until it's time to add seasoning and heat. I know I can get the prep done right but trying to guess what I've got before I take the 1st bite of any critter is a mystery to me.
Some of the finest venison I've ever eaten came from a Mule Deer buck that I watched running does for almost 2hrs. Tender, and no "gamey" taste at all, virtually indistinguishable from beef sirloin. Not an ounce of fat left on him. 1yr later I killed another what I believe to be younger deer in a similar situation running does, no fat left, etc and it was the toughest game meat ever. Flavor was fine but it left meat-slivers between every tooth in my head.
Carcass smell isn't a very good indicator either IMO. Elk stink WAY more than any deer. Sagey, piney, pissy stink with a hint of sweaty horse as well. Moose carcasses smell worse than elk. Antelope have that sage hot-blood stink too but elk, moose, and antelope are all exceptional in my experience.
There probably is something to aging game meat. On a caribou drop-camp hunt we had no cooler/ice. The meat layer out open-air in the shade for 5 days. Night temps were just above freezing, days in the low 50's. The backstraps I brought home were "fork-tender" and very mild.