Welcome to Cruise Critic. Interesting first post. Sad you would let an experience with Italian customs ruin your cruise experience.
Our daughter has an Italian passport. She breezed thru customs. We did not. They wanted to examine everything to see if duty was owed. Just like you, I think we were selected because we had a couple of expensive name brand items.
And yes, it took over an hour. Nothing is efficient or easy to accomplish in Italy.
I understand a complaint to Italy, but surely you understand that Celebrity or the United States government is not involved in how Italian customs does their inspections.
A question. . . How was your cruise? Do you have a "review" of your experienceon board?