Gluing pvc quarter round in the shower corner
I'm guessing the "ugliness" is wide enough that a good bead of white caulk, which you'd expect in a shower corner, won't solve the problem. in that case, this will work fine and is something I've done before. One suggestion would be to use some  dabs of fast drying epoxy to secure it in place and then clear silicone caulk both sides of the corner trim, and the top and bottom. The reason for this is if you just use caulk you'll be holding the corner in place until the caulk hardens to prevent the corner from separating from the wall..... that will take a while. You might be able to tape it in place temporarily but that sometimes doesn't work. Good luck.