Sorry for the delay. Had to wait for one of my managers to be in (one that has sailed many times). Disney Dollars are accepted, however you goto Guest Services and put them on your ship account, just like placing cash down. So not accepted in the actual shops, but still accepted.
Disney Dream - Dec 2012 4n Bahamas
Carnival Imagination - Dec 2011 4n Western
Carnival Imagination - Nov 2010 4n Western
Costa Atlantica - Dec 2009 7n Eastern
My opinions are mine and mine alone. They do not represent the opinions of The Walt Disney Company nor any of its subsidiaries.