My worst experience was also my first experience cruising. It happened on our honeymoon cruise 12 years ago this month. The cruise line NCL. The ship The 'New' Sunward. The details..
(We are contemplating a
DCL cruise in the next year so I have been lurking here..)
Here is our story.
We had been scheduled to cruise on NCL's Sunward II. A rather small ship but I guess typical for 12 to 15 years ago.. Anyway, NCL merged or bought out Royal Viking Line and sold the Sunward II and we saled on the 'maiden' voyage of the New Sunward, which I think was the old Royal Viking Sun (or Sky I forget). Here are the events as I recall them..
1. Get to miami airport, get picked up by NCL. Ship not ready they are taking us for an afternoon of 'shopping' at Miami's Bayside resort. The tell us it is hot and that we need to give them our carryons and they will deliver them to room so we don't need to lug them around the mall. Ok, no problem give them bags.. (More on this later)
2. After sweating it up in Miami in our travel clothes we get on ship and explore. Lots of old plates and cups from Royal Viking lines laying around, but didn't think much about that. We have the lifevest drill and no one comes to 'drill us.' Everyone around us on deck has a crew member. Ours isn't there. She shows up late and looked like one of the Goth characters from the SNL skit. She didn't know how to put on a lifevest. We were scared.
3. Get to our room. No bags and TWIN BEDS. HELLO HONEYMOON..

We requested something larger than twins, of course. Called them and they said they would fix it. Room steward came and pushed beds together. Ok.. (more on THAT later) Our bags still had not been delivered. Remember we had been out in the sun all day and wanted to dress for dinner. No bags. We waited and waited and ended up going to dinner in our sweaty clothes.. Fun! Sit down at a table for 8?! Another couple sits down. Within 5 minutes they get up to leave, the wife is seasick, bad. Never see them the rest of the cruise. My new wife and I sat at a table for 8, alone, for the whole cruise. (Maybe because we smelled

actually ship was only half full since this ship carried more than the old SunwardII and sitting alone was fine with me..)
4. Go back to the room and bags have arrived!! However the room reeks of Obsession for men cologne. Why? Well my carryon bag had the cologne and it was a leather carry on. The bag and its breakable contents destroyed! Everything in the bag that was breakable including a huge plastic handled brush was broken. The cologne seeped into the leather. In fact that bag still smells 12 years later. LOL!
5. Decide to take a shower. AHHH COLD WATER. NO HOT WATER. Called steward sorry sir we are having problems with the water heater.. The whole 4 nights cold showers. Wonderful on your honeymoon!
6. Second night rough seas. Woke up in the middle of the night because the twin beds had seperated and my wife had fallen through to the floor. I made a joke about the Poseiden adventure. Didn't make her laugh.
7. Our room was a suite on the promenade deck. Opened drapes one morning another honeymoon couple was on the deck, um, well lets just say they should have been in their room.
8. Paid for a tour of Nassau of the sights. The driver stopped at every street corner naming the trees. I don't recall any sites, just trees.
9. Last morning walking around the deck early before we had to leave. Stood watching them unload bags and found out what happened to my carryon. Watched them THROW all the luggage. Often times over there heads. We watched no less then 3 bags open and them stuffing clothes back into bags. Couldn't take it anymore and left.
Anyway there was more, but it was just a commedy of errors. We look back on that cruise fondly now and laugh a lot about it. My wife has been on a cruise since with her sister when her sis graduated H.S. and they had a great time.. We did leave from Miami and were in a concierge room at the Polynesian and at the time that more than made up for the "Cruise from Hell" as we affectionaly called it.
Sorry for the long read, but hope you found it funny.