Is what I've heard about Carnival true?

As others have said, not necessarily. Usually, the three day sailings are more likely to be the party hardy crowd. Carnival bills itself as the line for the whole family (both for cost and activities).

Not necessarily...you'll find unruly kids, drunks, and holier-than-thou know it alls everywhere, including up to and especially cyber. Take a cruise, on a given line, run into a "problem", and suddenly the whole line, and every ship in it becomes suspect. I've cruised several lines...including CCL, NCL and an assortment of others. My preference du jour happens to be NCL, but that doesn't mean much to someone else. If you insist on traveling during, say, spring break, you're going to get the usual obnoxious immature types...sometimes that includes adults too...There are folks in here who "are of an age" shall I say, who can clearly cruise ANY darn line they like, with dozens of cruises under their belts..and actually PREFER cruising CCL. There are folks who had a bad experience many years ago on a given ship, and will NOT even consider cruising the entire line again..no matter what..Their choice, not mine......

EVERY ship I have been on has an "adults only" section...some better organized than others. The food isn't what it used to be, but thats another story. The prices can range from "reasonable" (YOU decide what that is) to outrageously overpriced (YOU decide what that is as well..) Which is your preference, sailing on a so-called "lower-priced" line and discovering its just fine thank you, or paying thousands extra expecting a "higher class clientele" and discovering the obnoxious types are on there too....and it wasn't worth the price of admission?

What IS true, is that back in the day cruising was a big deal...for retirees, or rather well-to-do types...sometimes folks would save FOR years to do a once-in-a lifetime cruise...going back to the old country, or a special occasion like an anniversary..and possibly never cruise again...nowadays, anybody with a piece of plastic can do it, often for no reason at all....and so, you get ALL types...almost everywhere...the idea that you can pay more and guarantee that the cruise will go the way YOU expect it to is unrealistic. For example, the idea that those "inside cabins" are populated with kids who are just looking for an excuse to drink and play musical beds is patently untrue. There are folks onboard who can afford to book that ANY cabin if they wanted, or a Penthouse Suite, and choose to travel on an inside, just a place to sleep, shower and stash their stuff. I've met them...amazing travelers...

There is such a thing as "a cruise within the cruise"...I had no idea what that meant until I did it enough to figure out that ANY cruise is what you make it...and there ARE ways to make it more personally enjoyable, and not necessarily more expensive...on ANY ship..cyber has its place for some kinds of data and reviews and such, but there is NO substitute for your own experience...and sometimes gaining it can get expensive..GOOD LUCK!!!

Not everything you hear or read is true. Although Carnival has the reputation and promotes itself as the fun cruise line it is usually up to the cruiser what they want. Ships are larger enough to accommodate many types of people. But in general if you want laid back and quiet I would say that is Princess or HAL or Celebrity. If you want more upbeat, Royal or Carnival and if you want the least structured that would be NCL. In my opinion at least.

I don't think so. We've been on 10 Carnival cruises and I'd say over the past few years there seems to be more middle-aged to older guests than those that are younger. The only rude or unruly behavior I've seen was before the mustering procedure was updated. Back then, everyone had to report to their muster station on the deck outside, and stay in a line until everyone was accounted for. Considering that some of the passengers had been on board for a couple of hours, and the bars were open all that time you can imagine that there would be a few bad apples. With the new "self-mustering" that's no longer an issue. My only complaint is that the dress code for the main dining rooms isn't enforced. It's not unusual to see a few people (of all ages) wearing things that are specifically prohibited.

The "big", mass market cruise lines, like Carnival, Royal, NCL, MSC etc see a surge at spring break of younger guests. So wouldn't say its an issue with one single line. They seem to get more press, but that too may be part of the marketing strategy to draw a more rambunctious clientele as it shows a lot of people having a good time - hence you keep your ships full and the parties going.

I sailed Carnival once with our extended family. it wasn't during spring break so not many kids - mostly adults. But decided once was enough - the experience wasn't aligned with our personal vacation expectations, so we moved on to other lines.

You need to sample around to experience what line/ship type fits your personal vacation expectations. Its a personal choice. You can read all sorts of reviews, in reality, I find reviews to be jaded, so will try it and draw your own conclusions.