I know that on Seabourn, my main cruise line, guests have been banned over the years for various reasons, the top one being physical, sexual, and/or verbal assaults towards guests or crew.

Just a few days ago, a guest was offloaded from one of their expedition ships due to his behavior; he has a neurological disorder that causes him to offend and annoy guests and crew all the time, and he was constantly complaining (on the ship to everyone and on social media alleging discrimination) and demandng special treatment and exemptions from normal acceptable behaviour. After too many warnings, he was finally kicked off the ship, to everyone's relief.