I've always suspected that people who do not enjoy deer steak or roast have had them overcooked.

For roasts, I use a meat thermometer and cook them in the Weber Kettle - but not directly over the coals. When the internal temperature hits 120 the roast comes off the pit. I'll sometimes go as high as 130 if someone demands "well done", but never higher than that. But as Bronko said, all the fat must be removed.