Meat will keep indefinitely in the freezer set at 0 degrees or below, according to the USDA. However, certain circumstances arise that affect the quality of the meat. It's not necessarily spoiled, but the quality suffers to the point it should be discarded rather than cooked and served. General consensus is that meat should be used within four to 12 months of being frozen.
The recommended setting is 0 degrees or below. If the temperature increases above freezing because the freezer was unplugged or the freezer is overloaded with unfrozen foods all at one time, meat can spoil. To prevent the freezer from being unplugged inadvertently, place a piece of duct tape over the plug while it's in the electrical socket. The tape serves as a reminder. If a power outage occurs, a full freezer that was at 0 degrees will keep the food frozen for two to four days.
Freezing doesn't necessarily kill bacteria, mold or fungi that is already present. If the meat was starting to spoil before freezing, it will still be spoiled when you remove it from the freezer. The process of defrosting accelerates the spoiling process.
If you've noticed a grayish-brown, dry, leathery-looking spot on meats, then you know what freezer burn looks like. Exposure to freezing air dries out the meat. It's not spoiled, but it won't cook properly. Cut off the freezer burned areas. You could try making stews or soups out of the meat.
Purchase a freezer/refrigerator thermometer to accurately determine how cold your freezer is. Spoiled meat has a putrid odor and looks slimy. If the meat is on the verge of spoiling, it may smell odd but not actually bad. If there's any doubt, do not consume the meat. Don't try to cover up the odd smell with seasonings.