If you’re not sure how to tell if a butternut squash is bad, there are a few things you can look for. First, check the outside of the squash for any signs of mold or decay. If the squash looks bruised or has any dark spots, it’s probably not good to eat. Second, give the squash a smell test – if it smells sour or off, it’s probably not good to eat. Finally, cut into the squash and take a look at the inside flesh. If it looks discolored or has any mushy spots, it’s probably not good to eat. If you’re still not sure, err on the side of caution and throw it out.