I can't speak for all the CMs but I do know that the entertainment people probably don't have it as bad as some of the other ones. As you know, they are there to entertain so they have their shows to do plus numerous other appearances but they do get time off and chances are when you are at port and are shopping, they are likely right beside you
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I believe they are allowed to roam the ship as long as they are in "Disney attire", so you likely wouldn't even know who they are. They are also actually paid quite well.
Disney is a very good cruise line to work for and they treat the entertainers very very well. Their flights are paid for and in case of an emergency, Disney is absolutely top notch in what they provide to them.