Re- Roman coins in the headlines.
I have not seen the article myself, however, I would like to add a little ditty or two for you to comment on. As you say, it sounds as if they are talking about the coinage of the "Empire". i.e. silvered antoninnianus, follis etc.
But what of the "Republic"? I think the same debasement was abound. What of the denarius known as "The Fourree"? As far as I am led to believe, this was a piece of bronze totally clad in silver, and then struck as a denarius proper. These fourree types of denarius are fairly plentiful, and I have seen examples dating as far back as 131 bc. A few examples, L. Postumius Albinus, T. Cloelius 128 bc, C. Porcius Cato 123 bc, L. Flaminius Chilo 109-108 bc, C. Servilius 82-80 bc, and there are plenty more. As you quite rightly say, a true denarius should show no deviation in purity.
In conclusion and my opinion, any denarius that has a porous looking surface, or a flaking (plated) look about it, is a definite no go. Leave well alone. As for drilling or cutting into the coin, they must be mad! Whatever happened to x-ray or spectrograph analisys?
An interesting discussion item. I hope I have given a little help towards the topic.