Customers,however, will try and sneak DG onto aircraft without the crew's knowledge and hope that those going through the paperwork will have done their DG course long ago enough to be hazy on the subject.
When working for an airline that did not allow DG to be carried at all (ACMI) and despite specifically telling the client this, they onloaded several boxes containing concentrated Coca-Cola syrup. An eagle eyed Purser who was checking the paperwork noticed this and reported it to the Captain who had it offloaded.
On investigation, the offending paperwork was stuffed in the middle of all the rest of the stuff that the Purser was given by the dispatcher in the hope that it wouldn't be noticed or just plain misunderstood. This was from a major, well respected bucket and spade airline in the UK.
Fortunately all Flight Deck, CC and Ops staff in our airline had to be qualified in DG up to Air Loadmaster standard. This was valid for 2 years and a refresher in between. Certainly worked.
The point I try to make is that if ALL Flight and Ops staff were similarly qualified it would help. I know that the two frt outfits I worked for in the past trained their aircrew in DG.
Doc C