I admit when I saw "underground swamp rock" I thought that meant zydeco, but The Merry Jaynz are not zydeco. Maybe that is only for Louisiana. The Merry Jaynz are from South Knoxville, Tennessee.
Their red, yellow, and green, along with the name, made me think they might be a little more reggae in nature, or at least hippie. That isn't exactly right either.
As it is, in addition to there being room for different misguided ideas about the band, there is also room for more than one kind of band.
When the songs are instrumental, they are really catchy bass-driven funk. "A Thing" and "Soulmate" have completely different moods and are both excellent.
When voices come in, the instrumentation is the same but the sound is not.
The messages are often on point; "Most of Us (Dead)" sounds horrifyingly accurate. However, the voices are kind of distorted, giving the music an almost psychedelic feel. It reminds me of the music of a lot of my more counterculture friends.
That gives me some guilt about liking the instrumental tracks better, but taste is subjective. I can give The Merry Jaynz credit for filling two very different needs.