Whenm we took the transfer from Orlando airpott to Port Canaveral, we had our carryons loaded on the motor coach. When we arrived, our carryons were put into huge metal bins for transport to the ship, along with everyone else's large suitcases. We had to haul a few of the suitcases out of the way to grab our carryons (as we only travelled with carryons) and then the porters were all standing around with their hands out saying "dont' forget to tip your porter" - it was really in the face and annoying. So we tipped them, then about 10 yards away as we walked towards the port building there was a sign posted stating: "baggage porters are salaried, tipping not required."
While I certainly believe in tipping when service is warranted, I don't need them standing there literally begging for tips. I felt sorry for them as obviously they don't get paid very much. But I didn't see any of them offer to get my bags out of the luggage bins for me as I was trying to get to them.
The next time I cruise, I will make sure to keep my carryons on the coach with me - they do have some overhead compartments for that or you can fit them in front of you on the floor. If that's not possible, then I'll make sure to have a porter grab my carryons, and that person will get the tip.