Nope, no hassle. You just walk up to the window, hand the person your passport along with your pre-filled forms, they hand you your room key, go through security & off you go!!
We never saw police dogs on our cruise, but I guess it depends on what port you are leaving from? What cruise were you looking at?
Expect security if you are leaving out of NYC. We're on a higher terror alert than the rest of the country because of the Financial district.