We just cruised on carnival Ecstasy and we experienced the same thing. The first night out we ordered drinks from a waiter and we noticed they were very weak. So the next round we ordered I walked up to the bar to watch but it was obvious to me that the bartender went out of his way to get out of my line of sight. These were weak also. Next night we ordered the “double” but these were weaker than they should have been. We tried different bars with same results except the margarita pitcher at the blue iguana ( this comes out of a tap premixed ). We’ve never had this problem before. We don’t buy the drink plan which they seem to be really pushing. They scan your card before they make your drinks so it would be easy to “tag” certain passengers as “good tippers” or “special guests”. Otherwise we had a great cruise. We just got our drinks ashore before boarding and also drank the wine we brought with us.