How long is canned ham good for left out of the fridge?
It depends on if it was shelf stable or marked “keep refrigerated”.

From Arizona Cooperative Extension


  Canned hams labeled “keep refrigerated” require refrigeration and, unopened, will keep 6 to 9 months in the refrigerator. Once canned hams are opened, keep them refrigerated and use within 3 to 5 days. Make sure the can isn’t showing any bulges, cracks, dents or rust, or leaking any liquid. A canned ham should not be frozen. Shelf-stable canned hams do not require refrigeration and may be stored in a cool, dry place for 2 to 5 years.


From USDA


  Refrigerated - May be stored in the refrigerator for up to 6 to 9 months. Its weight can be up to 8% more than original uncured weight due to the uptake of water during curing. It need not be labeled "Added water" except for "In Natural Juices." Net Weight is the weight of the actual ham excluding the container. Processed at a cook time and temperature sufficient to kill infectious organisms (including trichinae); however, the ham is not sterilized so spoilage bacteria may grow eventually.