Yes it can. This is why you train. After the foundation work is done, later PP work is spent on control and everyday situation training. For instance, in the DSO, there are several scenarios where the draw is not the intended target or threat. One scenario is where you are heeling in a straight line, as a loud man waving a cane is upset because he has "lost his glasses." The person flails the stick screams loudly and makes a fuss. This is very enticing for a dog, but after a certain point to your side a mugger steps out, points a gun at your head and says quietly,"give me all of your money." The dog is convinced it knows who the threat is, when in fact it is a passive threat. Training such as this prepares a handler for these types of situations. The dog and handler communication and the wariness as well as the actions the handler take are integral to a good PP dog. It is work. These types or scenarios help to teach the handler how to deal with these situations as much as it teaches the dog the difference in the reaction of its owner when under threat or not. A naturally defensive dog may be intolerant of rough play from neighbor kids, or buddies rough housing. A trained dog may also react, but knows when to " stand down," at the owners request, but also can read the owner's intention and "feelings" about the actions taking place. Part of the training is to think about what you would do in such a situation. For instance, I get loud, defensive, and aggressive; so when training, I get loud, defensive and aggressive. Some in our group scream when "attacked." Others are more passive. It is a personal level of communication with your beast. :)