The die hard loyal of any cruiseline will stay for the most part. I've had a few from various lines who love that line, have a bad experience of one kind or another and swear they'll never return. They often cruise once with another line and their next booking go back without ever bringing up the problems again. We're all creatures of habit and all have preferences for whatever reason. I think the cruiselines know this well and exploit it. I even had a lady permanently confined to a wheelchair that had a truly disturbing situation. She called me on her cell from one of the early ports requesting to fly home and filed suit against a particular line, justifiably I might add. She cruises about 6 times a year and spends more than most of us could dream of on her cruises. After getting home and filing the suit she booked a cruise with another line. Before she ever boarded the ship one of her friend told her she'd never sail with her choice of replacement cruiselines and she cancelled. She called me for advice and I gave it to her the best I could knowing she absolutely loved the line she was suing for years until this horrible incident (I can't/won't go into detail). She hung up without booking anything, great help I was! About 2 weeks later she dropped her suit and booked not one but 3 more cruises with the line she dropped the suit with. She has never mentioned it again.
Until we, and I include myself, really do decide we'll stick to our guns when they drop the ball badly we'll continue to perpetuate this problem. I have my own preferences but limit my endorsements to what I feel fits each clients needs, wants, lifestyle, age, etc. I also keep a close eye on what my clients are saying when returning from specific ships. You'd be amazed how quickly a ship can go from recommended to "Let's see if we can find some other options here..." Sorry for the long post.