The older Carnival ships are some of the worst for that. Their designer at the time would settle on a color theme and then it would be all you could see. We sailed on one ship that had these ugly turquoise eggs EVERYWHERE (Carnival Paradise), the Fantasy is all neon lit purple, the Victory all neon green. It's so bad.
Most of my experience lies with Carnival, its the one we almost always sailed as kids (except for a couple detours to Disney Cruise Line and then on Princess as we got older), and now my husband prefers Carnival because it's more casual. He doesn't like the elevated dress code requirements for the dining room on most other ships. In his opinion, he's paying $X for this vacation, and if he feels like wearing jeans to dinner in the standard dining room after a long day in port it shouldn't be such a big deal-he dresses up for formal nights or the higher dining restaurants without complaint, its just the regular dining room that he thinks should be more casual. So, Carnival it is for now (until I can convince him otherwise).