I have an inherited non-enameled cast iron dutch oven. I've made chili in it several times and coq au vin once. Despite all the warnings, I (and others) don't notice any problem with taste or color; I did the coq au vin for a big crowd so we used an enameled one as well for the other batch & I did not notice the difference.
Am I missing something? or is it that I just don't know any better or my guests are being over-polite?