Interesting question if they knew about the worm quality of their work. Obviously they wanted to create music that one could listen to repetitively. I notice no difference between the brother's work, actually some of the older work is more worm-worthy to me.
Perhaps it's because that music was shared between my older sister and me? We were far enough apart in age that the BG's were some of our only common artists we could tolerate.
I do think some artist's are more earworm worthy than others. But I found a new(old) one the other day. Instant worm for me. YMMV.
Tom Petty and Mudcrutch: Lover of the Bayou:
With lyrics like these:
And I've got cats and teeth and hair for sale
I'm the lover of the bayou
Baron Samedi is on your tail
I'm the lover of the bayou
I cooked the bat in the gumbo pan
Drank the blood from a rusty can
Turned me into the hunger man
I'm the lover of the bayou, yeah