Oh, it's typically well-made, it's just harder to be positive about it when I've sung the first line to myself a couple of thousand times.
Where do people have earworms? (Apart from their ears, presumably.) I get them at work, when I generally can't drive them away with other music, and often when I'm out walking.
Something I dread on a long walk is getting a classic fast twelve-bar backing track stuck in my head, a bit like this:
which I may not get rid of for miles.