Well, if you count nearly giving me a heart attack every time I decide I should probably shower and making me debate wether personal hygiene or peace of mind is more important for my wellbeing as doing no harm, then yeah. She's doing no harm at all.
Come to think of it, there's a spider living somewhere in my shower aswell. She's smarter than yours though. She appears randomly before me whenever I don't expect to see her, yet is miraculously nowhere to be found whenever I come back to try and get rid of her. I have a suspicion she's doing...
We used to have a cat when I was really young. Too young to be around a cat unfortunately, since I kept chasing it around the house because I wanted to pet it. Poor thing. :(