I think there are a lot of variables at play. I don't say that everyone who books the least expensive cabin is an "undesireable" passenger. HOWEVER, cheaper fares (come on folks there are some 7 day cruises going for under $300pp) will allow a lot more people to get on board, so to speak. Many of these passengers would not otherwise cruise. Some may not have a special affinity for "the way it was" ---and the mega liners with ice skating rinks, rock climbing walls, Burbon Street replicas designed to convicne passengers they are anywhere but on a cruise ship--and that might affect their behavior.
My first cruise I paid $650 for a 7 day inside upper/lower in the single share program.
My second cruise cost me (solo passenger) over $5000. My up coming cruise will top both at over $8000. To be honest, I did not notice any outrageous or rude conduct from passengers on my deck (also in steerage) and my tablemates (I do not know their cabin category as none of us discussed that at dinner) were perfectly gracious. If there was any officious behavior it escaped me or I have blocked it out.
My second cruise was in a top suite not the penthouse but the next one after that. And my third cruise was in the same category on the same ship. Neither my manners nor my mind have changed since the first cruise, though my bank account has. I was brought up with manners & adhered to proper ettiquete then & now. However, some of my fellow passengers in the most expensive accomodations aboard have been down right vulgar & rude.
I'm not implying that there are drunken rousts on the suite deck, but vulgarity takes many forms. I'm talking condesending to staff, impatient, selfish & just general unpleasant behavior. Some are better pleased with what they think of themselves than what they see in their fellow passengers. And for some stupid reason often times I am expected to chime in since we're in the same 'zip code'. When they saw I was traveling alone & in top diggs they asked if I was upgraded. After saying no, all the Jones' seemed to stop by constantly. Is that proper behavior? No, but they did it anyway.
Noxious behavior & personalities know no economic boundary. Unruly children are a different matter completely as their is no excuse for that. I speak mostly of adult passengers. By point is that cabin cateogry & price paid do have an impact on passenger behavior. It just goes both ways.