Some of these hosts have been consecrated; some not. Can you tell which? Carl from Atlantic City can.
I'm not sure how else a person could distinguish them-- the Church certainly doesn't claim a chemical distinction. I think anyone expecting that the host is going to turn green and be emblazened with 'Christ was here' is a nut. But my experience of the Eucharist-- of that spiritual distinction-- has been profound and life-altering.There are more cracker threads at Pharyngula than I can count, each with bajillion posts. You will not believe your eyes.
Added: The crackers need a few friggin' lazers on their heads. Then they could say convincingly, "U THREATEN CRACKERS?!! OMG U IZ SO DED!!1!" But that's beyond my time and/or shoopin' skills.