Through instinct/taste/habit. When I first started going rawpalaeo, I couldn't stand the taste of raw meat if I'd left it in the fridge for more than 2-3 days after sale.Gradually , I got used to the taste of fresh, raw meats which I'd left for much longer periods(10 days/2 weeks etc.) until , eventually, I managed to get used to and even enjoy "high-meat"(meat aged 3-4 weeks in the fridge at not too high a cold-setting).
Just take your time and work out, via experimentation, how fresh you need your raw meat to be, before you can't handle the taste. Eventually, you'll get used to raw meats left out for longer periods.