How can you tell if your cashew milk has gone bad? If it is past the freshness code on package?  
Yes, it can go bad.  The date on the package is one indication, but it may be a "best by"  date and does not guarantee the milk will go bad by then. It doesn't necessarily mean it is guaranteed safe, either, although most stores will give you a refund on product that spoils early.  Look for the following signs (written for almond milk, but cashew milk follows the same rules):        the container seems abnormally bloated after opening     mold is present     any funky or pungent odors     the product has curdled or is visibly thick and slimy (observe the consistency when putting)     a change in color, as almond milk may appear more yellow when it has spoiled      Source 