We often combine a title and subtitle for this reason. What we strive not to do is make stuff up. The key to a good HN title change is that it is made out of pieces already there: doc, h1, and h2 elements, mostly; or the first sentence of the story, if necessary. If the original title is misleading or linkbait, that is how we change it. But if the original title isn't misleading or linkbait, we don't change it at all.