I think it is important to go on any cruise with the idwea that you will not let a staff person ruin it for you. It has happened to me, so I know, but that is still the best advice.
If the staff was rude to you on Costa they have no excuse. You should be treated like anyone else. And not to have anyone to complain to is also frustrating.
We suggest people should get the name of a rude crewmember and write a note to the hotel manager. Turn it in to the front desk i9n an envelope saying "to: hotel manager" with your cabin number inside. He will get the message and so will the crewmember.
As far as "stink" goes, a lot of ships "stink" at times, just like hotels and school cafeterias do.