The fist to check is Soundtrack. Usually it's related to Le Fabuleux Destin d'Amélie Poulain. I've heard that it is due to a popular pirated copy of it is tagged with Soundtrack as the artist. The files are also write protected so persons with low computer skills may not be able to fix the tags. Also check the related Soundtracks and Original Motion Picture Soundtrack.
Some other generic non-artists that needs to be checked are Video Games, Theme Songs and Videogames.
Hairspray is a house group. Some people like to upload movie posters for the movie with the same name.
Several artists are called Wicked. Some people like to upload posters for the musical by Stephen Schwartz with the same name (see Wicked (Original Broadway Cast)).
Some people like to upload pictures of building to Original Broadway Cast.