J. Lo is really, REALLY bad. It's beyond having a thin and characterless voice--she is simply tone-deaf and for all her lack of range she cannot sing on-key.
Heidi Montag -
Justin Bieber - I will love his voice....if he is a GIRL
Taylor Swift - she sucks live.
Miley Cyrus - Oh well, some of her songs are catchy.
Ke$ha has an amazing voice. Autotune is just messing up with her