I am very very honest. If I don't like a client, I just keep quiet, but I can be very complimentary!
Recently, I was able to come in oral for the very first time. I didn't have a clue what the guy was doing, but I told him he did. I am not sure if he believed me though. There is also a guy I have seen a couple of times who has the nicest pad ever, the decor is amazing and it's just a lovely place. I have told him twice now and he obviously is very pleased haha! There was also a guy who was bloody gorgeous who booked me once and I said to him. My regulars know that I am sincere, I will always be honest and tell them if I don't like something they do as well.
I will always compliment someone if I mean it, else I stay quiet.