I have a niger, snowflake eel, blue headed wrasse, purple lobster, yellow tang, bi-color angel, black angler, and my cleaner shrimp.
maybe i'm just lucky but my cleaner shrimp is always sitting some rock cleaning the face of my eel or back of my niger and wrasse sometimes even my angler....so
i have to say it's possible.
and no, it's not a joke.