I'm startled by the tone of a few recent comments. Some people are feeling uncomfortable, but they respond with general condemnation of others rather than specific useful contributions. Either that or recent visitors are just more noble and high-minded, and therefore more easily disgusted and prone to the curled lip than than the rest of us are.

Anyway, back to the specifics of the real world. One problem of the UK position on parodies I outlined above is that someone can copyright a tune from public domain, then collect on your new words to that tune. An example is The Hokey Cokey - Jimmy Kennedy heard it sung in London by Canadian soldiers, added a rotten verse nobody uses, and retired on the proceeds. He used the traditional lyrics for all but the verse.