Harvey's a great songwriter, and Margarita's one of my favourite songs. If I heard someone singing it in a way that seemed to spoil it, I'd feel defensive about it too. But that isn't the same for me as saying that there is one set of word fixed in stone

Songs are slippery things. Even in the mouths of the person who makes a song up, it changes. I've even heard people complain because a singer doesn't sing a song the same way they sang it on a record, not because they've spoiled it, which might be fair, but because they've changed it.