Excellent examples sir of what I was talking about. The first coin has rudimentary wings, static robes, and a stiff body. The second example has lifelike wings and robes, and fully three dimensional facial features and body. While the first would be labeled acceptable work, the second truly was the work of a master celator.
I think that "I know it when I see it" is as good an answer as anyone can give. Judgements of style are subjective, there's no way around it. Sometimes maybe we can make a judgment about the level of skill that went into making something, but that doesn't always correlate to 'fine style.' I think we've all developed an ideal of what ancient art should look like based on other things we've been exposed to, especially Renaissance art; we tend to prefer the ancient works that resemble those over those that don't.