For those not familiar with the show, they take a young fan, and have them "become" their favourite musician (Madonna, Avril Lavigne, Pink, etc.).
They don't ever meet the star, but they go through the star's makeup artist, hairdresser, wardrobe, etc. If they're really lucky, they get a letter from the star! Ooh!
I find it creepy because it shows such blind image worship, while dehumanizing the artist. Madonna isn't a woman, she's a construct of makeup, choreography, fashion, etc.