Antelope is wonderful game meat. Proper field care is very important as stated above, but this is really the case for all game meat.
On occasion I have had an antelope that even the dog wouldn't eat. This is rare, but maybe 10% of antelope for one reason or another are not good table fair. This is even after proper care and cooling of the meat.
I have experienced something similar with Caribou, on occasion. Most are decent eating (though not as good as antelope) but sometimes there is nothing you can do to make the meat edible.
I have often theorized for antelope that the bad ones had been running hard, etc., but have no evidence to back that up. For all I know they ate some bad feed the day before, or have a "cold", or some other anomaly that is not observed. I am just back from a weekend shooting does with my wife, and will begin taste testing each animal tonight.I'm confident we have some quality meat on ice at present.
Bill