Happy singer with happy songs: Cyndi Lauper, Stevie Wonder, Keith Urban
Happy singer with sad songs: Adele, John Legend, (early) Coldplay
Sad singer with happy songs: Fountains of Wayne, Jellyfish, lots of power pop
Sad singer with sad songs: Kacey Musgraves, Pete Yorn, James Taylor
Uniformity and juxtaposition are powerful tools in music.
