Picked up a case of wine from Alex last week and flew back through EZE to IAD on United.

Checking the wine with United was zero problem. At IAD, used Global Entry but truthfully answered the questions triggering an "X". Went to the CBP desk and the person was entirely confused on what to do with the "X" card and went on for five minutes on how I was idiotic to declare my wine, how it didn't matter if I answered the questions truthfully, etc. etc. She logged into my CBP record that I brought in a case of wine, handed me back the "X" card and sent me on my way to get my baggage.

At the area where the CBP person collects the forms issues started. Why do you have an "X" card? What is in your box? etc. etc. Finally decides to send me to the "C" area where another CBP person gets annoyed why I am in that line, that he has to search all of my luggage, etc. I get another 5 minute speech on why I was stupid to declare my wine and tell the truth on the Global Entry computer.

After the search, the CBP person marked my account stating I brought in wine over the limits, but it was duty free this time. He told me if I brought wine over the limits again in the future, I would be charged duty.

Moral of the story - don't declare your above-limit wine at IAD.