I'm looking to add Karaoke to my DJ services to make some extra money on weeknights at local bars, etc.

A lot of the karaoke services I'm finding have songs with FULL VOCALS on them... what's the point? Why would you want to try and sing OVER someone already singing on the recording? Why not just play the REAL version of the song in that case?

Anyway, anyone have suggestions for good karaoke music subscription services that sound minimally cheesy and don't have vocals on their tracks already?

Seriously, am I missing something? I've never gone to a bar or place with karaoke where their tracks had vocals on them...