The fact is pretty much all of my complaints with Magic could be taken care of by Carnival with regular maintenance. It doesn't take a drydock to replace the upholstery in the MDR. They can do that in phases on turnaround/port days. They can add extra scrubbers in the casino to clear smoke any time. They can enforce their smoking rules and kick people off who break them anytime.
The fact is, Carnival doesn't care that their ships look nasty. If they cared, they'd fix the problem. Actions (or rather, lack of action) speaks louder than words.