I certainly wouldn't call them "wrecks"!
I wonder if any of them make those skulls out of marzipan? I'd be all over one of those! I had a birthday cake many years ago with marzipan frogs on it but this is even better.
And Dia de los Muertos has been a great inspiration...
If I had to guess, I'd say most of the sculpting is modeling chocolate. Marzipan is definitely a possibility, but is best suited to accents, in my opinion. More elaborate decoration is more easily sculpted with modeling chocolate, and larger decoration is often done with crisped rice and covered.