"it's the lyric that makes a song a hit"
I don't understand the lyrics in Portuguese of some very known earworms.
Do native speakers understand the pronunciation of Curt Cobain? Likely,
but I guess not many people else. What about earworms such as
Serenade No. 13? It's easy to understand the lyrics of the Beatles, even
with broken English, but a lot of people don't understand their lyrics,
still like the earworms.
No, a tune makes a song an earworm and heavy rotation makes a song a
hit, if you play a 3 minutes recording of a jackhammer by heavy rotation
on radio and TV, it will become a hit. I would prefer my neighbour would
listen to jackhammer recordings instead of the four to the floor
recordings he's listening too, it would be less psycho-terror for my
taste, there are more nuances by a jackhammer.