Excellent post, and welcome to the AnFam!

I just read an article not to long ago about the inscription on the denarius, and it seems to suggest Ceasar was descended from/was "God." Viewed from this vantage "Whose image is this, and whose inscription?" can be viewed as an extremely clever way to ask "Is Caesar God to you? Do you believe the inscription? If so, pay him--your "God." If not, pay God."

Just my thoughts, and always an interesting Jesus reply to think about.