Most dog owners, at least most of them who have and use suitcases on occasion, believe that their dogs have figured out the significance of luggage.
"Oh no, he's noticed that I have my suitcase out -- he'll be whining constantly until I actually get out of here," or "until my dog-sitting buddy comes to get him," or whatever. We've all heard such sentiments. It seems superficially plausible. After all, wouldn't a dog who has seen his humans leave and return carrying such bags come to associate them with abandonment?
Well ... maybe. But there seems to me to be a simpler hypothesis. Maybe the dog doesn't recognize the suitcase or whatever, and not recognizing it is the problem. Perhaps the suitcase is simply a fairly large object, a piece of furniture, suddenly dropped into familiar surroundings. Certainly dogs do like the familiar surroundings to remain as they are.
The act of moving a sofa from one side of the room to the other would probably upset most people's dogs. Thus, we shouldn't necessarily assume that the upset caused by baggage is inherently different from that.
Reckless anthropomorphizing, ya know.