I wasn't having a bash at you! Sorry if you thought so.
But the Capt. does not (theoretically) have any right to refuse (he certainly has no right to accept) DGR if the paperwork and loading procedures are followed.
I know of 1 SQ Capt many moons ago who did refuse to carry a shipment on a 747-300 Combi, he was severely reprimanded on return to base (perhaps that's SQ?!), but I wouldn't count on much support if you dd refuse a shipment (therefore company revenue) unless you are 100% sure that the cargo staff/loading staff have messed up big time.