officially, the concierge is a 'non-tipping' position....
i.e., you're not supposed to tip them and they're not supposed to accept it...
i can't tell you whether they refuse or not as they did absolutely nothing for me, so there was no reason to tip them....
in fact, i only met them on friday at the concierge cocktail party....we chitchatted for about 10 minutes....but that was the sum total of my interaction with the concierge staff....
so i saw no reason to tip them....
on the other hand, we had two stateroom hosts instead of the normal one....the second one was in training and i was told that it was a non-tipping position....however he was the sweetest person you can imagine....always smiling and cheerful....so i tipped him anyway as i felt he deserved it....
as for all the other tipping positions....i didn't follow the guidelines...i felt they all deserved much more than what the guidelines stipulated, so i tipped them much more........(and they were very very gracious and appreciative....i think not so much for the amount as for the fact that we were so very pleased with their efforts to make our cruise the wonderful experience that it was...)