I have once, There was nothing wrong physically with the client, I just couldn't stand his mannerisms any longer, it was either tell him to leave or risk losing my temper with him and telling him what an arrogant prick he sounded, there are a few clients I refuse repeat bookings from and it's usually to do with their personality/hygeine rather than looks/physical appearance, once I don't like someone I would prefer them to see someone else so they don't bring me bad energy and they don't waste their money, .   99% of the clients I see are lovely, but it's impossible to gel with every single client.

Actually twice, one came in and looked liked he was homeless or his boiler and washing machine had
broken, saying sex sex sex in broken English, I literally just said come on now out you go, frog marching him back out of the door. Even if he didn't ask for sex I wouldn't have massaged him.