Depends on how spoiled it is. Because there is more microbial activity, your sugar content is going to be a lot lower than fresn sap e.g you aren't going to get the ratios you would with fresh sap. Naturally occuring microbes and yeasts convert the sugars in the sap. So, lower ratios. Older sap will also make darker syrup. Personally I like the darker stuff more and it wouldn't bother me. If sap is too far gone you will make syrup with off flavors. Judgment call on your part. You can smell and taste the sap. If it tastes bad chances are the syrup will taste bad as well. Good luck!
2 x 6 arch, custom raised flue pan, AOF/AUF
18 x 22 timber frame shack
Two little girls that are a LOT of help
Greyhound that drinks sap
2011 Gator 825 XUV with 150 gallon tank
3 275 gallon IBC totes for storage