I have always been in the habit of tipping a higher percentage when service is exceptionally good. If my waiter..busboy or other waitstaff are good to me, I will honestly tip them higher than the minimum. I don't think Carnival is doing a good by this. When I sail, I will request that all automatic tips be removed and I will tip myself, and if they decent, polite and provide good customer service, they will probably get more than the "auto tip"... I think Carnival has listened to one too many consultants.