I get rather annoyed when people badmouth Carnival, as I've done some great cruises with them. As some other posters have pointed out, you have to be selective.
My last cruise pre-Covid was a 13-day Panama Canal full transit on the Carnival Miracle. Very adult passenger mix but very high energy. One of my best cruises.
HAL cruisers may not want to hear this, but my best Alaskan cruise was an 8-day on the Carnival Miracle. It was the last cruise of the season, mostly adults, and absolutely perfect. The day we spent in Glacier Bay was stunning. I've never been so up close to the glaciers.
The 12-day Hawaiian cruise I took on the Carnival Spirit was also a great cruise.
On my most recent Noordam cruise, I mentioned my Panama Canal experience on Carnival to another cruiser. He asked me why I wanted to be on a ship with 800 kids. Most families can't afford a 13-day day Panama Canal cruise on any line. I'd be surprised if there were 8 kids on the cruise, let alone 800.