Between my Dad and I we have probably shot 100 from Northern WY to Southern CO, both sides of I-25. Full on sage (which they only eat if they are starving or weird BTW) to full on corn and wheat. I have had ones that taste good and ones that are not as good. Care and processing of the meat can certainly cause you issues. I have also found that if you don't hang it to cool for a day or two, it is not as good.
When it is warm, I toss a pallet in the truck. After a kill, we put the animal, skin on, on the pallet and pack the cavity with ice. The ice and the airflow around while driving has been the ticket for me.