Each de-mangling step decreases a "cost" metric on the text, based on its length plus the number of unusual combinations of characters. It never really decides

Each de-mangling step decreases a "cost" metric on the text, based on its length plus the number of unusual combinations of characters. It never really decides that text is "okay", but when there's no step it can take that decreases the cost, it's done. This is an imperfect greedy strategy, incidentally. If it takes multiple steps to fix some text, it's possible that the first step it needs to take is not the one that decreases the cost as much as possible, that it has to go through some awful-looking intermediate state so that everything falls into place for the next step. This is rare, though. I don't think I could come up with an example.