Not sure if this is the problem but lots of unknown artists can get on your playlists because they list other more famous artists as collaborators on their tracks. Every now and then you'll also get an unknown artist naming their band the same as a more famous band. These usually get moved or removed fairly quickly but it can be annoying when they show up in your playlist. I get one or two every week showing up on my release radar. I have no idea how they get on spotify in the first place.