Below is a list of moods for K.K. Slider songs:
Good!/Happy: Most of these songs are awesome or happy-sounding.
A little sad.: Most of these songs have nostalgic or gloomy feels, hence the use of "A little sad".
Lazy: Most of these songs are either relaxed like Aloha K.K., or a mix between the "Good!" and "A little sad" moods like I Love You, K.K. Love Song, or Mr. K.K.
Grumpy: Most of these songs sound intimidating or grumpy.
Hard to say.: These songs are plain or neutral sounding, but ones like Agent K.K. and K.K. Gumbo have a mix between the "Grumpy" and "Lazy" moods.