Or even orange-named for that matter?
I noticed yesterday some bosses seemed to ignore my Song of Capering. Today I ran a couple quests far below level, and watched "Combat" tab. Whenever I hit a trash mob, a line would appear "You hit a [mob] with Song of Capering". When I hit a boss, nothing at all would happen. And it is not because they were tough -- Lotigath the gargoyle in Cerulean Hills (CR 4) ignored Song of Capering, as did the boss sahuagin in Storehouse Secret.