usually in stories and fiary tales, good spirits are nice, helpful, drawn beautifully, and every bad thing they do is out of a mission they need to accompish. bad spirits in stories are mean, ugly, cruel, and usually powerful enough to be bad, although in the inside, sometimes they are actually good, which hints that good and evil spirits are not that clear.
in real life, good spirits and evil spirits are unidentified clearly, but people identify them according to their own opinion of what is good and evil, and everyone's opinion is different, so you can't really tell, unless you have your own 'rubriç' of what's good and bad, and decide depending on actions the victim being decided if they have a good or bad spirit or not make.
the answer is that there is no standard answer, and you can't really tell, at least, not now.(unless you make the rubric of deciding up that can be used widely in all cases)
