I'm with oregonmarkv on this one, but I'll throw in some what it depends also and just my personal opinion nothing scientific or specific. Bacteria starts setting in immediately when an animal dies, it's no doubt worst depending on size of animal , how thick the hide is, what the outside temperature is, has the animal died in the shade or open sunlight area, and also where you hit the animal. I'll use elk as an example because I'm primarily an elk hunter but deer can be thrown in there also. This is one reason marksmanship is really important e.g. gut shoot it and it spreads all sorts of bad things all over inside the animal none of which is good for you if you don't get it cooled down and cleaned up asap and especially true if it's warm out. I've killed elk/deer and it was so cold out we didn't even skin them until the day before we left for home, BUT we field dress them and take out the esophagus and pry open the chest cavity to let cold air in. Usually when it's this cold the animal freezes and not a big deal if you have done the above, better yet would be to skin them when first shot more because it's easier and you can clean up any blood shot areas that the hide may be hiding. I'm going to use elk as an example they are big /heavy and have thick hide and don't cool down fast in cool to mildly cool weather, when it's warm you will lose them to bacteria if not cooled down immediately. You can smell it , where it starts to spoil first no specific order on large animals is the neck area, deep down in the heavy bone areas like next to the hip bones and such, might feel cooler to the touch on the burnished areas on the outside, but stick a knife it to the bone and feel the inside meat temperature only to find it's not cool at all. In Arizona where we live even in the mtns 60 degrees out during the day you better get that meat cooled down. We've had to pack 200 lbs of ice in an elk cavity to save it. if it smells bad at all you will know the meat is bad. Deer are much smaller and will cool down faster , but 40 to 60 degrees out on an animal that hasn't been gutted and field dressed and left for that long I don't know. To be honest with you I'm not so sure even if you can't smell it soured it still might be bad, in any case if it's bloated at all, done deal it gone.